APA (7th ed.) Citation

Packer, L. S., & Eiss, N. S. (1958). Phase-plane graphics, a new approach to teaching dynamics. American Journal of Physics, 26, 91.

Chicago Style (17th ed.) Citation

Packer, L. S., and N. S. Eiss. "Phase-plane Graphics, a New Approach to Teaching Dynamics." American Journal of Physics 26 (1958): 91.

MLA (9th ed.) Citation

Packer, L. S., and N. S. Eiss. "Phase-plane Graphics, a New Approach to Teaching Dynamics." American Journal of Physics, vol. 26, 1958, p. 91.