Engelken, R., Engelken, R., & Slattery, P. (1981). The art of natural farming & gardening. Barrington Hall Press.
Dyfyniad Arddull ChicagoEngelken, Ralph, Rita Engelken, and Pat Slattery. The Art of Natural Farming & Gardening. Greeley, Iowa: Barrington Hall Press, 1981.
Dyfyniad MLAEngelken, Ralph, et al. The Art of Natural Farming & Gardening. Barrington Hall Press, 1981.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.