Sulyok S, Wankell M, Alzheimer C, Werner S (octubre de 2004). «Activin: an important regulator of wound repair, fibrosis, and neuroprotection». Mol. Cell. Endocrinol. 225 (1-2): 127-32. PMID 15451577. doi:10.1016/j.mce.2004.07.011.
van Zonneveld P, Scheffer G, Broekmans F, Blankenstein M, de Jong F, Looman C, Habbema J, te Velde E (2003). «Do cycle disturbances explain the age-related decline of female fertility? Cycle characteristics of women aged over 40 years compared with a reference population of young women». Hum Reprod 18 (3): 495-501. PMID 12615813. doi:10.1093/humrep/deg138.