APA (7th ed.) Citation

Shaeffer, R. E. (1983). Calculator layout, the numerical concept. Ralmar Press.

Chicago Style (17th ed.) Citation

Shaeffer, Ralph E. Calculator Layout, the Numerical Concept. Portland, OR: Ralmar Press, 1983.

MLA (9th ed.) Citation

Shaeffer, Ralph E. Calculator Layout, the Numerical Concept. Ralmar Press, 1983.