O'Hara, B. F., Smith, S. S., Bird, G., Persico, A. M., Suarez, B. K., Cutting, G. R., & Uhl, G. R. (1969). Dopamine D2 receptor RFLPs, haplotypes and their association with substance use in black and Caucasian research volunteers. Human Heredity, 43(4), 209-18. https://doi.org/10.1159/000154133 (Original work published 1969)