Irwin, K. L., Rosero Bixby, L., Oberle, M. W., Lee, N. C., Whatley, A. S., Fortney, J. A., & Bonhomme, M. G. (1988). Oral Contraceptives and Cervical Cancer Risk in Costa Rica: Detection Bias or Causal Association.

Irwin, Kathleen L., Luis Rosero Bixby, Mark W. Oberle, Nancy C. Lee, Anne S. Whatley, Judith A. Fortney, och Michele G. Bonhomme. Oral Contraceptives and Cervical Cancer Risk in Costa Rica: Detection Bias or Causal Association. 1988.

Irwin, Kathleen L., et al. Oral Contraceptives and Cervical Cancer Risk in Costa Rica: Detection Bias or Causal Association. 1988.