Chiwakata C, Brackmann B, Hunt N, Davidoff M, Schulze W, Ivell R (1991). „Tachykinin (substance-P) gene expression in Leydig cells of the human and mouse testis”. Endocrinology. 128 (5): 2441—8. PMID1708336. doi:10.1210/endo-128-5-2441.
Chiwakata C, Brackmann B, Hunt N, Davidoff M, Schulze W, Ivell R (1991). „Tachykinin (substance-P) gene expression in Leydig cells of the human and mouse testis”. Endocrinology. 128 (5): 2441—8. PMID1708336. doi:10.1210/endo-128-5-2441.