Robin Baker[англ.], Sperm Wars[англ.] (2006), ISBN 978-1-85702-356-5, стр 140:"Actual figures range from 1 percent in high-status areas of the United States and Switzerland, to 5 to 6 percent for moderate-status males in the United States and Great Britain, to 10 to 30 percent for lower-status males in the United States, Great Britain and France."
