APA (7th ed.) Citation

Mendes, M. F., Guerreiro, G., & Caleiro, A. (2013). Fertility in Portugal, How persistent is it?

Chicago Style (17th ed.) Citation

Mendes, Maria Filomena, Gertrudes Guerreiro, and António Caleiro. Fertility in Portugal, How Persistent Is It? 2013.

MLA (8th ed.) Citation

Mendes, Maria Filomena, et al. Fertility in Portugal, How Persistent Is It? 2013.