Cita APA (7th ed.)

Christensen,Howard B. (1977). Statistics step by step. Houghton Mifflin.

Cita Chicago (17th ed.)

Christensen,Howard B. Statistics Step by Step. Atlanta: Houghton Mifflin, 1977.

Cita MLA (9th ed.)

Christensen,Howard B. Statistics Step by Step. Houghton Mifflin, 1977.