Depends on what you are after.
https://www.amazon.com/Beatles-Anthology/dp/0811826848
https://www.amazon.com/Complete-Beatles-Recording-Sessions-1962-1970/dp/0600635619
https://www.amazon.com/Beatles-These-Years-Extended-Special/dp/1408704781
https://www.amazon.com/Paul-McCartney-Many-Years-Now/dp/0805052496
https://www.amazon.com/As-Time-Goes-McCartney-Harrison/dp/0571342663
https://www.amazon.com/George-Harrison-Living-Material-World/dp/1419702203/
https://www.amazon.com/Postcards-Boys-Ringo-Starr/dp/081184613X
https://www.amazon.com/Photograph-Ringo-Starr/dp/1905662335
https://www.amazon.com/Beatles-Book-Hunter-Davies/dp/009195861X/
https://www.amazon.com.au/John-Lennon-Letters/dp/0316200808
https://www.amazon.com/Beatles-Illustrated-Record-Roy-Carr/dp/B003D7D3II