This is the 20th post in a weekly, yearlong series. Read about it here and see the list of previous songs here. A new post about a different song will be posted each Monday throughout 2016. You can listen to the songs in a Spotify playlist.

When ABBA recorded its self-titled third album in the spring of 1975, the band’s members worried they would never again achieve the success or fame they had with “Waterloo” in 1974. That track had done well in most of Europe, but it was the band’s only single that had resonated in the UK. With the subsequent hits flopping in Great Britain, the band feared it would be dismissed there as another one-hit wonder produced by the Eurovision Song Contest.

But the band plugged away on “ABBA,” resigned to the fact that it would not fare well in the UK. “Mamma Mia” was the last song recorded for the album. Benny Andersson and Bjorn Ulvaeus wrote the song in the library of the house Ulvaeus shared with Agnetha Faltskog. Ulvaeus was the band’s principal lyricist, but many of the song titles, including “Mamma Mia,” had been floated by the band’s manager, Stig Anderson. Anderson and the band hoped phrase, which is Italian for “my mother,” would be a catchy, “international” song title that would have appeal in many countries. “That turned out to be another distinctive and memorable title, and one that maybe a native English writer would have thought was too European — and very uncool,” Ulvaeus wrote in “Mamma Mia! How Can I Resist You?”

In April 1975, the band recorded short promotional videos for four songs from “ABBA”: “Mamma Mia,” “SOS,” “I Do, I Do, I Do, I Do, I Do,” and “Bang-A-Boomerang.” But the band assumed those videos would be used to promote the album in its entirety, rather than specific, individual singles. Thus, the band and its management assumed that “So Long,” “I Do, I Do, I Do, I Do, I Do,” and “SOS” would the three singles released. But the four videos proved popular among Australian audiences, as they had been played repeatedly on television. RCA, ABBA’s record company in Australia, pleaded with ABBA’s main record company, Polar Music, to give permission to release “Mamma Mia” as a single. After initially refusing, Stig Anderson relented. “We wanted to find out what the potential of ‘Mamma Mia’ was, how strong it was,” he said.

The single topped the Australian charts for 10 weeks, attracting the attention of ABBA’s record company in Great Britain, Epic Records. “SOS” had just been released as a single in the UK, becoming the band’s first British Top Ten hit since “Waterloo.” When “Mamma Mia” was released in the UK, it became a Number One hit in January 1976. It reached Number One in Ireland and Germany, and fared well in countries across the world, giving the band international fame and ameliorating any concerns the members had about being a one-hit wonder.

In 1983, a year after ABBA disbanded, Ulvaeus and Andersson worked on the musical “Chess” with Tim Rice. During that time, Ulvaeus and Andersson met producer Judy Craymer, who thought ABBA’s pop songs lent themselves to being a musical. Despite not being initially enthusiastic about the idea, the songwriters came around. A script was written in 1997, with a director coming aboard the following year.

“Mamma Mia!” premiered in London’s West End in 1999, playing at the Prince Edward Theatre till 2004, when it transferred to the Prince of Wales Theatre, where it played for the next eight years. The musical opened on Broadway in October 2001, and in 2008, a film version starring Meryl Streep, Christine Baranski, Pierce Brosnan, Stellan Skarsgard, Colin Firth, and Amanda Seyfried premiered.

One of the first covers of “Mamma Mia” was actually an ABBA medley, Norman Gunston’s “Salute to Abba.” Gunston was the alter ego of Australian actor and comedian Garry McDonald, who first created the character on Australia’s “The Aunty Jack Show” in 1973. Gunston was portrayed as a dull and bumbling reporter who would ambush people for interviews, not unlike Sacha Baron Cohen’s Borat character. Gunston’s self-titled 1976 album featured takes on many songs, including “Jailhouse Rock.” His “Salute to Abba” sounded like Ian Dury and the Blockheads had gotten drunk and decided to play at a dueling piano bar. Which, ya know, sounds very plausible.

In 1995, New Zealand recording label Flying Nun Records put out “Abbasalutely,” a tribute album of ABBA covers by New Zealand bands. Noise pop band The 3Ds’ cover of “Mamma Mia” was pretty faithful to the original, but took off some of the polish of the pop song. The opening notes, done with a marimba in the ABBA version, sounded somewhat ominous in The 3Ds version. That led into the familiar riff, played on guitar that not crunchy, but distorted enough to sound contemporary enough for the post-grunge mid-’90s. Denise Roughan’s sang Agnetha Fältskog’s and Anni-Frid Lyngstad’s parts in a twee pop way, which also gave the song a modern feel, albeit subtly.

English dance-pop/Hi-NRG singer Hazell Dean included “Mamma Mia” on her 1996 album, “The Winner Takes It All: Hazell Dean Sings ABBA.” The iconic marimba appeared at the song’s beginning, but was sped up and accompanied by a drum machine beat that quickly led into the opening verse. Dean didn’t sound drastically different from Fältskog or Lyngstad, except for a few parts in the chorus where she went deep with passionate Bonnie Tyler-esque vocals. The nuances of Ulvaeus’s and Andersson’s arrangement were lost to the flourishes of dance-pop, as the track more closely resembled Dutch Eurodance group The Vengaboys’s “We Like to Party (The Vengabus)” than anything ABBA produced. But, like that Vengaboys song, Dean’s “Mamma Mia” was deliciously cheesy and unabashedly campy.

Christian ska band Five Iron Frenzy covered “Mamma Mia” on its 1998 7″ single, “Miniature Golf Courses of America Present Five Iron Frenzy.” The original song’s signature riff translated surprisingly well with the band’s guitar styles, but otherwise it sounded like what you might imagine a late ’90s ska version of “Mamma Mia” to sound like: bright horns, pounding drums, groovy guitar riffs, and “Why did you take away my allowance?” emo vocals.

Swedish pop group A*Teens was initially meant to be an all ABBA cover band, called ABBA Teens. Ulvaeus and Andersson worried that would cause confusion, so the group acquiesced to the name change. A*Teens’ first album, 1999’s “The ABBA Generation,” featured pop and electronic updates of ABBA hits. Like Dean’s Hi-NRG version, A*Teens’ “Mamma Mia” overlaid a drum machine beat over the familiar riff, but otherwise, it sounded rather faithful to the original. The one change, besides the drum machine, was its omission of the second refrain:

Mamma Mia, even if I say
Bye bye, leave me now or never
Mamma Mia, it’s a game we play
Bye bye, doesn’t mean forever

It was a Number One hit in Sweden and reached the Top 20 in almost every European country.

Pop-punk/ska band Human Hamster Hybrids covered “Mamma Mia” for its 2001 album “Dance Classics.” The band’s take on the song sounded a little more aggressive than Five Iron Frenzy’s ska version, starting with the opening of the song, a sample of Bender from “Futurama” saying, “Hey! What kind of party is this? There’s no booze and only one hooker.” The guitars were crunchier, the drums heavier, and the vocals more assertive.

Boston band Seks Bomba had a style that blended swing, bossa nova, and lounge music. The band’s cover of “Mamma Mia” from its 2005 album “Thanks and Goodnight” had elements of all those genres, but the backing instrumental track started out uncannily like Eddie Money’s “Baby Hold On.” As Seks Bomba’s “Mamma Mia” continued, though, Lori Perkins’ organ and Chris Cote’s vocals gave the song a feel that sounded more like a late ’60s soul song than a mid-’70s pop hit.

In 2006, German AC/DC tribute band Riff Raff released an all-ABBA cover album, “Rock ‘N’ Roll Mutation Vol. 1: Riff Raff Performs ABBA.” The twist was that all the songs were performed in the style of AC/DC. The band’s take on “Mamma Mia” had parts of Ulvaeus’s and Andersson’s arrangement, but also relied on a bluesy riff that looped throughout the song. And unlike the ABBA version, the Riff Raff version had a pretty sweet guitar solo about three minutes into the song. The vocals were not a bad approximation of Bon Scott and Brian Johnson, but with a mix of Axl Rose, a similarity that only recently became fitting.

Riff Raff was not the only AC/DC tribute band to record “Mamma Mia” in the style of AC/DC. BandX featured the song on its 2010 album “Wild Ride.” Whereas Riff Raff’s version was a slowed down version that had a chugging riff not unlike David Bowie’s “The Jean Genie,” BandX’s version sounded like a cross between AC/DC’s “You Shook Me All Night Long” and The Cult’s “Love Removal Machine.” As convincing as the vocals were on Riff Raff’s “Mamma Mia,” BandX’s version sounded even more authentic, sounding exactly how you would expect AC/DC would have played the song had the band written it. Between the distinctive guitars and thebackground vocals on the “My, my, how can I resist you” line, I’m not entirely convinced this version was not by AC/DC.

Danish power metal band Seven Thorns covered “Mamma Mia” on its 2014 album “II.” The song opened with some of the best ’80s metal cliches: eery synthesizers reminiscent of Europe’s “The Final Countdown,” singer Erik “EZ” Blomkvist’s moans of “Ohhh yeah,” and pounding Metallica-esque drums. Those flourishes, however cheesy they appear when reading them listed together, worked very well for covering “Mamma Mia.” It might be a cheesy metal cover, but it is very tongue-in-cheek, not unlike the campy pop song that inspired in the first place.

The versatility of “Mamma Mia” highlights the beauty of most ABBA songs: Ulvaeus’s and Andersson’s arrangements were not dependent on particular style of music, but catchy hooks, and that’s a feature that’s genre-agnostic. The basic structures, as we have seen, translated into multiple types of music, including ska, pop-punk, twee, Hi-NRG, and metal. Just consider the line “Just one look and I can hear a bell ring/One more look and I forget everything.” You’re singing that in your head now, aren’t you? Maybe even moving your arms in the air? That melody and arrangement is a fist-pumper in any language, in any style of music.

In that regard, these covers of “Mamma Mia” are like the covers we looked at when discussing “Tears Of A Clown.” There are some covers that are going to be more palatable than others, depending on one’s preferences, but the source material is so good that one has to work really hard to make a version of “Mamma Mia” that is so bad and so unlistenable that the basic melody does not get stuck in your head.

But ABBA covers are not like most of other songs we’ve discussed, because of the added component of the musical and the movie. The musical and subsequent movie were essentially a new way to present ABBA’s biggest hits. It’s a fun, silly story, but the music is no different from the music released on the albums. Should the performances in the movie version or each stage production of the musical count as ABBA covers? They should count as new versions, but should they get the word “cover”? Musicals have been revived and performed by multiple casts for years. It’s the very nature of musicals. We wouldn’t call Neil Patrick Harris’ performances of the songs in “Hedwig And The Angry Inch” cover versions of the original musical, so why would we do it with the songs in “Mamma Mia!”? Should the fact that the songs were recorded by an individual band more than two decades before the musical premiered be enough reason to create an “I before E, except after C” exception?

Bands have recorded songs from musicals and operas for years, and those are definitely covers. We have no problem saying Me First And The Gimme Gimmes covered a song from “Phantom Of The Opera.” Would we say the same thing if that recording had had come from a stage production of the entire show in which Me First And The Gimme Gimmes had been the performing band? Is the absence of the live stage version the distinguishing line between performing a song in a subsequent production and recording a cover of a theatrical song for an album?

When we looked at “I Say A Little Prayer,” we included the version performed by the cast of “My Best Friend’s Wedding.” That’s become an iconic version of the song, even if it’s not the definitive take. Should that be considered a cover? What about the version of “The Loco-Motion” that’s featured in the Carole King musical? Whatever rule that’s applied to that should certainly be applied to the movie and musical versions of “Mamma Mia,” right?

These questions, as hairsplitting as they might seem, seek to distinguish the differences between an “alternate version” of a song and a “cover song.” As we have seen in these last 20 posts, there’s more to being a cover than just not being the original recording of the song, and quite often, the distinctions can be rather squishy.

You can listen to these songs and previously discussed cover songs in a Spotify playlist.