Beethoven. Ed. H.C. Robbins Landon. London: Macmillan, 1970. 400 pp.
The standard book which contains contemporary accounts of Beethoven by his friends, enemies, peers, etc. Also contains a very good selection of pictures of important Beethoven people, etc.
For other documentary or illustrated biographies, search in the Beethoven Gateway in the Category index (search terms: documentary biographies; iconographies).