Bev Bevan, the drummer throughout the band's career, evidently functioned as something of a band historian. Also, having been part of the Brum community of up-and-comers (equally the calibre of the Liverpool lads, though one hears considerably less about them) he was also around for the salad days, including being one of the core members of Roy Wood's famous band Move (the one which gave birth to ELO).
In 1980, at the inflection point after Out Of The Blue and before Discovery he compiled words and images into a published history of the band to that point. The book, with the rather un-preposessing title of The Electric Light Orchestra Story, told the story of those early days through the big time of summer and lighntning (and the great glowing hamburger) from an upclose, personal, and frank (though nuanced) point of view.
Toward the end there's even a section with a brief bio of each member, including what city they lived in and marital status.