title: A plea for data on the sexes of human offspring and the time of formation of the zygotes within the fruitful cycle.
authors.forename: William H
authors.initials: WH
authors.lastname: James
mesh_terms: D005260:Female; D006801:Humans; D008297:Male; D008597:Menstrual Cycle; D011247:Pregnancy; D012744:Sex Ratio; D013997:Time Factors; D015053:Zygote