Guzick , D . S . , S . A . Countifaris , J . W . Overstreet , P . Factor - Litvak , M . P . Steinkampf , J . A . Hill , L . Vogel and R . E . Canfield . 1999 . " Efficacy of Superovulation and Intrauterine Insemination in the Treatment of Infertility . " New England Journal of Medicine 340 : 177 - 183 .