His An experimental study of the permanence of course material ... 1938.

His The great psychologists, c1991: CIP t.p. (Robert I. Watson, Sr.) galley (d. 1980)

LC database, Oct. 27, 2011 (hdg.: Watson, Robert Irving, 1909- ; usage: Robert I. Watson [with or without "Sr."; predominant form], Robert Irving Watson, R.I. Watson)

OCLC, viewed February 28, 2025: (access point: Watson, Robert I. (Robert Irving), 1909-1980; Watson, Robert Irving; Watson, Robert I.; Watson, Robert I., Sr.; Watson, Robert I., 1909-; Watson, R. I. (Robert Irving); Watson, R. I.; usage: Robert I. Watson; Robert I. Watson, Sr.; R.I. Watson; or not shown)

Library of Congress database, viewed February 28, 2025: (access point: Watson, Robert I. (Robert Irving), 1909-1980; usage: Robert I. Watson; Robert I. Watson, Sr.; or not shown)

University of New Hampshire, "University of New Hampshire, the graduate school, 1975-1976" (1975), Graduate Catalog 40: page 144 (Watson, Robert I.; Professor of Psychology; Ph.D., Columbia University, 1938; appointed 1967) https://scholars.unh.edu/gradcatalog/40

Ancestry[dot]com, viewed March 4, 2025: (Robert Iriving Watson; birth: 10 May 1909, East Orange, New Jersey, USA; death: 15 Sep 1980, Gainesville, Florida, USA)