In the uber pop phenomenon that was ABBA, one could barely imagine there could be any more surprises - especially for diehard fans.
But now after 40 years comes an extraordinary collection of photographs - from the iconic to the intimate - with many being published for the first time.
ABBA The Official Photobook is a treasure trove for anyone on the ABBA fan spectrum, featuring images of the Swedish supergroup at work, play and, most candidly, at home.
Released to coincide with the 40th anniversary of the group's historic Eurovision win, the authorised collection records the stories behind some of pop music's most enduring images and moments.
One of the most famous of countless ABBA images is the helicopter cover of the 1976 album Arrival.
Photographer Ola Lager explains he waited all day for the right light in which to capture the group next to the Bell 47 chopper, a former air force training machine that had been repurposed for transport around the Stockholm archipelago.
Although the light was perfect for Lager's shot, there was one problem - he could be seen in the cabin's glass.
"My wife and the pilot, Olle Wikman, helped out by holding up sheaves of long grass to hide me in the reflection."
After the photo shoot, Benny and Frida went with Wikman for a joyride - a shot that makes it into this book.
From the moment ABBA won the Eurovision Song Contest in Brighton on April 6, 1974, with Waterloo, their every move was starting to be recorded by photographers.
Two images show how far the band was prepared at the time to allow the media access - Swedish photographers were in the couples' hotel rooms to catalogue them in bed for what appears to be the morning after.
Bjorn says: "Looking back, it's weird that we went along with it, but we were so tight with the media, almost cuddly."
As the group's fame increased, their image was more carefully managed.
Take, for instance, the photo of the young foursome clad in nothing but tin foil.
Frida recalls of the 1975 shot: "I think it's fun. Did we wear panties underneath? Of course. Bras too, if I remember rightly. We just pulled down the straps so they wouldn't be visible."
There are pages upon pages to delight Australian fans, when the group visited in 1976 for TV music show Bandstand and the following year for their hugely-anticipated national tour.
The reader can also see inside Stockholm's Polar studios where ABBA recorded many of their albums, sales of which now number some 400 million worldwide.
The studio was built inside a former cinema and, when it closed in 2004 - after recording other artists including Led Zeppelin and Roxy Music - there were suggestions it be turned into a music museum.
Agnetha says: "The Polar studio was my home away from home. That's where I enjoyed my job the most, and there were times when I was just full of joy."
Of course, the book showcases ABBA's colourful and outlandish costumes, including Frida and Agnetha's "cat and dog" outfits.
The book notes that part of the reason behind the "spaced out" designs was that Swedish entertainers could claim stage wear on tax - provided it couldn't double as part of their daily wardrobe.
Bjorn says: "In my honest opinion, we looked like nuts in those years. Nobody can have been as badly dressed on stage as we were."
* ABBA The Official Photobook - at three centimetres thick and weighing three kilograms - is written by Petter Karlsson with photo editor Bengt Wanselius and is published by Hardie Grant Books, RRP $75.
