Pierce, M. B., and D. A. Leon (2005). Age at menarche and adult BMI in the Aberdeen children of the 1950s cohort study. Am J Clin Nutr 82 (4): 733–39.

Pillard, R. C., and J. M. Bailey (1995). A biologic perspective on sexual orientation. Psychiatr Clin North Am 18 (1): 71–84.

Pillsworth, E. G., M. G. Haselton, et al. (2004). Ovulatory shifts in female sexual desire. J Sex Res 41 (1): 55–65.

Pinaud, R., A. F. Fortes, et al. (2006). Calbindin-positive neurons reveal a sexual dimorphism within the songbird analogue of the mammalian auditory cortex. J Neurobiol 66 (2): 182–95.

Pinna, G., E. Costa, et al. (2005). Changes in brain testosterone and allopregnanolone biosynthesis elicit aggressive behavior. Proc Natl Acad Sci USA 102 (6): 2135–40.

Pittman, Q. J., and S. J. Spencer (2005). Neurohypophysial peptides: Gatekeepers in the amygdala. Trends Endocrinol Metab 16 (8): 343–44.

Plante, E., V. J. Schmithorst, et al. (2006). Sex differences in the activation of language cortex during childhood. Neuropsychologia 44 (7): 1210–21.

Podewils, L. J., E. Guallar, et al. (2005). Physical activity, APOE genotype, and dementia risk: Findings from the Cardiovascular Health Cognition Study. Am J Epidemiol 161 (7): 639–51.

Prkachin, K. M., M. Heather, and S. R. Mercer (2004). Effects of exposure on perception of pain expression. Pain 111 (1–2): 8–12.

Protopopescu, X., H. Pan, et al. (2005). Orbitofrontal cortex activity related to emotional processing changes across the menstrual cycle. Proc Natl Acad Sci USA 102 (44): 16060–65.