https://pubmed.ncbi.nlm.nih.gov/2597859/
Harris B, Johns S, Fung H, Thomas R, Walker R, Read G,
Riad-Fahmy D. The hormonal environment of post-natal depression. Br J
Psychiatry 1989;154():660-7.
https://pubmed.ncbi.nlm.nih.gov/3923412/
Battin DA, Marrs RP, Fleiss PM, Mishell DR Jr. Effect of
suckling on serum prolactin, luteinizing hormone,
follicle-stimulating hormone, and estradiol during prolonged
lactation. Obstet Gynecol 1985;65(6):785-8.