Engel, George L. “A Unified Concept of Health and Disease”. Perspectives in Biology and Medicine, vol. 3, no. 4, 1960, pp. 459-85, https://doi.org/10.1353/pbm.1960.0020.
Engel, G. L. (1960). A Unified Concept of Health and Disease. Perspectives in Biology and Medicine, 3(4), 459-485. https://doi.org/10.1353/pbm.1960.0020
Engel, George L. “A Unified Concept of Health and Disease”. Perspectives in Biology and Medicine 3, no. 4 (1960): 459-85. https://doi.org/10.1353/pbm.1960.0020.
Engel GL. A Unified Concept of Health and Disease. Perspectives in Biology and Medicine. 1960;3(4):459-85.