In most libraries, biographies are NOT filed alphabetically by the author's last name. Instead, biographies are housed together, (in the 920 for collected biographies and in 921 for individual biographies). They are then filed alphabetically by the last name of the person the book is about.
The Blacker the Berry by Wallace Thurman
The Invisible Man by Ralph Ellison
Native Son by Richard Wright
Not Without Laughter by Langston Hughes
The Souls of Black Folks by W.E.B. Du Bois
Their Eyes Were Watching God by Nora Zeale Hurston