There's various places that provide data that show it's him
for instance, the education section on his resume: (also his prior jobs..left that out though)
COLLEGE EDUCATION
Santa Rosa Junior College, Santa Rosa, California ................
February 1947 to June 1949.....<redacted>....
A.A. degree.
University of Missouri.........Columbia, Missouri, ................
September 1949 to June 1952 and September 1953 to February 1954..........majors in English, philosophy and journalism..
B. A. degree.....
Montana State University , Missoula, Montana ...September 1954 to March 1955 and the summers of 1956 and 1957.....minors in creative writing and education.