Higgs, Philip, 1948-

Els, G., author.

Loubser, M. M., editor.

Harding, James, editor.

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

Bartol, Curt R., 1940- author.

Hibbeler, R. C., author.

Cottrell, Stella, author.

Sonnekus, J. C., author.

Masterskill.

Independent Institute of Education.

Independent Institute of Education.