1. Cunningham, G. R., Stephens-Shields, A. J., Rosen, R. C., Wang, C., Bhasin, S., Matsumoto, A. M., Snyder, P. J. “Testosterone Treatment and Sexual Function in Older Men With Low Testosterone Levels.” PubMed. Journal of Clinical Endocrinology and Metabolism. 01 August 2016. 2. Pendick, Daniel. “A Logical Approach to Treating Erection Issues.” Harvard Health Publications. Harvard Men’s Health Watch. 27 November 2012. 3. Zenico, T. Cicero, AF. Valmorri, L. Mercuriali, M. Bercovich, E. “Subjective Effects of Lepidium Meyenii (Maca) Extract on Well-Being and Sexual Performances in Patients with Mild Erection Issues: A Randomized, Double-Blind, Clinical Trial.” PubMed. Andrologia. April 2009. 4. Schottner, M., Gansser, D., Spiteller, G., “Lignans From the Roots of Urtica Dioica and Their Metabolites Bind to Human Sex Hormone Binding Globulin (SHBG).” PubMed. Planta Medica. December 1997. 5. Singh, S., Nair, V., Gupta, Y. K., “Evaluation of the Aphrodisiac Activity of Tribulus Terrestris Linn. In Sexually Sluggish Male Albino Rats.” PubMed. Journal of Pharmacology and Pharmacotherapeutics. March 2012. 6. Do, J., Choi, S., Choi, J., Hyun, J. S., “Effects and Mechanism of Action of a Tribulus Terrestris Extract on Penile Erection.” PubMed. Department of Urology, Gyeongsang National University Hospital. March 2013. 7. Prasad, A. S., Mantzoros, C. S., Beck, F. W. Hess, J. W., Brewer G. J., “Zinc Status and Serum Testosterone Levels of Healthy Adults.” PubMed. Nutrition. May 1996. 8. Kothari, R. P., Chaudhari, A. R., “Zinc Levels in Seminal Fluid in Infertile Males and It’s Relation with Serum Free Testosterone.” PubMed. Journal of Clinical and Diagnostic Research. May 2016. 9. Malviya, N., Jain, S., Gupta, V. B., Vyas, S., “Recent Studies on Aphrodisiac Herbs for the Management of Male Sexual Function—a Review.” PubMed. Acta Pol Pharm. February 2011.