Folders contain alphabetical files, some from separate stages in Professor Landsberg's career. These files were also sometimes gathered out of sequence and intermingled with other research file folders. Landsberg examined every aspect of John Dos Passos's life and career, conducting correspondence with anyone who might have known the author or had correspondence with him. He particularly researched Harvard contemporaries, especially those who might also have interacted with Dos Passos in Europe after graduation, during WWI, and during the Spanish Civil War.