“In 1970 the four of them went on a couples’ holiday to Cyprus, where they marvelled at the combined effect of their voices during evening singalongs. Within three years they had pooled their individual careers, and names, into Abba – with permission from the original Abba, one of Sweden’s biggest producers of herring.” The London Review of Books on their authorized biography “The Book of Abba: Melancholy Undercover” by Jan Gradvall. https://www.lrb.co.uk/the-paper/v46/n24/chal-ravens/twinge-of-saudade (probably paywalled)