The physical Heinrich Mann papers collection contains personal and business correspondence, manuscripts and published articles, short stories and reviews, personal documents and photographs, and pencil drawings dating from Heinrich Mann's years in France, 1933-1940 and Los Angeles, 1940-1950.
The digital collection available online at this site contains only selections from the physical collection.
See the physical collection finding aid here:
https://archives.usc.edu/repositories/3/resources/207