Berglund Scherwitzl E, Lundberg O, Kopp Kallner H, Gemzell Danielsson K, Trussell J, Scherwitzl R. Perfect-use and typical-use Pearl Index of a contraceptive mobile app. Contraception 2017;96(6):420–5. https://www.ncbi.nlm.nih.gov/pubmed/28882680
Duane M, Contreras A, Jensen ET, White A. The performance of fertility awareness-based method apps marketed to avoid pregnancy. J Am Board Fam Med 2016;29(4):508–11. https://www.ncbi.nlm.nih.gov/pubmed/27390383
