Procedural and Non-Procedural Query Languages Revisited: A Comparison of Relational Algebra and Relational Calculus. - Gary W. Hansen; James V. Hansen (Int. J. Man Mach. Stud., 1987)

Human Performance in Relational Algebra, Tuple Calculus, and Domain Calculus. - Gary W. Hansen; James V. Hansen (Int. J. Man Mach. Stud., 1988)

An approximate user-complexity measure for relational query language systems. - Gary W. Hansen; James V. Hansen (Data Knowl. Eng., 1991)

Direct Assessment of IS Student Learning using an Integrative Exercise. - Lynn J. McKell; Gary W. Hansen; Conan Albrecht (J. Inf. Syst. Educ., 2008)