APA (7th ed.) Citation

Harr, D. C. a., (curator), I. S. U. S. C. a. U. A., & Petersen, P. C. (1977). Douglas C. Harr letter to Peter C. Petersen regarding bird sightings, June 23, 1977.

Chicago Style (17th ed.) Citation

Harr, Douglas C.et al, Iowa State University. Special Collections and University Archives (curator), and Peter C. Petersen. Douglas C. Harr Letter to Peter C. Petersen Regarding Bird Sightings, June 23, 1977. 1977.

MLA (9th ed.) Citation

Harr, Douglas C.et al, et al. Douglas C. Harr Letter to Peter C. Petersen Regarding Bird Sightings, June 23, 1977. 1977.