Bull, J., Rowland, S., Lundberg, O., Berglund-Scherwitzl, E., Gemzell-Danielsson, K., Trussell, J., & Scherwitzl, R. (2019). Typical use effectiveness of Natural Cycles: Postmarket surveillance study investigating the impact of previous contraceptive choice on the risk of unintended pregnancy. BMJ Open.

Bull, Jonathan, Simon Rowland, Olof Lundberg, Elina Berglund-Scherwitzl, Kristina Gemzell-Danielsson, James Trussell, and Raoul Scherwitzl. "Typical Use Effectiveness of Natural Cycles: Postmarket Surveillance Study Investigating the Impact of Previous Contraceptive Choice On the Risk of Unintended Pregnancy." BMJ Open 2019.

Bull, Jonathan, et al. "Typical Use Effectiveness of Natural Cycles: Postmarket Surveillance Study Investigating the Impact of Previous Contraceptive Choice On the Risk of Unintended Pregnancy." BMJ Open 2019.