Commire, Anne, ed. Something about the Author. Vol. 1. Detroit: Gale Research, 1971. The article on Robertson provides some interesting information about how he came to be a writer and about his inspirations and work habits. It also contains a good-sized photograph of the author and two of Robert McCloskey's amusing illustrations from Henry Reed's Journey.

Kinsman, Clare, and Mary Ann Tennenhouse, eds. Contemporary Authors, First Revision Series. Vols. 9-12.

Detroit: Gale Research, 1974. The entry on Robertson covers his personal and career background and lists his publications and other sources of information on his life and work.

The Writer's Directory 1988-90. Chicago: St. James Press, 1988. Contains a brief biographical entry on Robertson, a list of his publications, and the address of his publisher.