1. Relative infertility: modelling clinical paradoxes;Jansen;Fertil Steril,1993
2. Fecundity and infertility in the United States, 1965-1988: advanced data from vital and health statistics;Mosher,1990
3. Are subfertility and infertility on the increase?;te Velde;Tijdsch Fertiliteit,1992
4. Fertility trends in Denmakr in the 1980s;Knudsen,1993
5. Worldwide patterns of infertility: is Africa diffrent?;Cates;Lancet,1985