Sterling, Mary Jane, author.

Loubser, M. M., editor.

Harding, James, editor.

Heaton, J., author.

Gravetter, Frederick J., author. (uri) http://id.loc.gov/authorities/names/n84044621 (uri) http://viaf.org/viaf/sourceID/LC 84044621 (uri) /resolver/wikidata/lc/n84044621

White, R. D. (Robert Douglas), 1956- author.

Bartol, Curt R., 1940- author.

Cottrell, Stella, author.

Masterskill.

Independent Institute of Education.

Independent Institute of Education.

Aertsen, Ivo, editor.