
The best biography is Rachmaninoff by Victor I. Seroff 1951. Amazon has two used and one collectible. Before Amazon existed, I had to ask a researcher to locate a copy for me.
A little tribute to Mom and Dad, and Tom, who died four months after Mom.
https://en.wikipedia.org/wiki/File:Rachmaninoff_-_Vocalise_transcribed_for_Violin_and_Piano.ogg