Gropper, G. L. (1991). Text displays: Analysis and systematic design. Educational Technology Publications.
Lua i Stíl Chicago (17ú heag.)Gropper, George Leonard. Text Displays: Analysis and Systematic Design. Englewood Cliffs, N.J.: Educational Technology Publications, 1991.
Lua MLA (8ú heag.)Gropper, George Leonard. Text Displays: Analysis and Systematic Design. Educational Technology Publications, 1991.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.