APA (7 वां संस्करण) प्रशस्ति पत्र

Engelken, R., Engelken, R., & Slattery, P. (1981). The art of natural farming & gardening. Barrington Hall Press.

शिकागो शैली (17वां संस्करण) प्रशस्ति पत्र

Engelken, Ralph, Rita Engelken, और Pat Slattery. The Art of Natural Farming & Gardening. Greeley, Iowa: Barrington Hall Press, 1981.

एमएलए (8वां संस्करण) प्रशस्ति पत्र

Engelken, Ralph, et al. The Art of Natural Farming & Gardening. Barrington Hall Press, 1981.