1. Abe, T. (2004). Sekkusuresu no seishin igaku (The psychiatry of sexlessness). Tokyo: Chikuma Shobo.
2. Atoh, M. (2000). Gendai jinkogaku (Modern demography). Tokyo: Nippon-Hyoron-sha.
3. Blanchflower, D. G., & Oswald, A. J. (2004). Money, sex and happiness: An empirical study. Scandinavian Journal of Economics, 106(3), 393–415.
4. Bongaarts, J., & Potter, R. G. (1983). Fertility, biology, and behavior: An Analysis of the proximate determinants. New York: Academic.
5. Brewis, A., & Meyer, M. (2005). Marital coitus across the life course. Journal of Biosocial Science, 37(4), 499–518.