APA (7th ed.) Citation

Lopker, J. (2000). Pictures of personality: Guide to the four human natures. Typology.

Chicago Style (17th ed.) Citation

Lopker, John. Pictures of Personality: Guide to the Four Human Natures. Typology, 2000.

MLA (8th ed.) Citation

Lopker, John. Pictures of Personality: Guide to the Four Human Natures. Typology, 2000.

Warning: These citations may not always be 100% accurate.