Parkes, A., Wight, D., Henderson, M., Stephenson, J., & Strange, V. (2009). Contraceptive Method at First Sexual Intercourse and Subsequent Pregnancy Risk: Findings from a Secondary Analysis of 16-Year-Old Girls from the RIPPLE and SHARE Studies. Elsevier.

Parkes, Alison, Daniel Wight, Marion Henderson, Judith Stephenson, and Vicki Strange. Contraceptive Method At First Sexual Intercourse and Subsequent Pregnancy Risk: Findings From a Secondary Analysis of 16-Year-Old Girls From the RIPPLE and SHARE Studies. Elsevier, 2009.

Parkes, Alison, et al. Contraceptive Method At First Sexual Intercourse and Subsequent Pregnancy Risk: Findings From a Secondary Analysis of 16-Year-Old Girls From the RIPPLE and SHARE Studies. Elsevier, 2009.