TY - JOUR A1 - Gyllenborg, J. A1 - Skakkebæk, N.W. A1 - Nielsen, N.C. A1 - Keiding, N. A1 - Giwercman, A. T1 - Secular and seasonal changes in semen quality among young Danish men: A statistical analysis of semen samples from 1927 donor candidates during 1977–1995 Y1 - 1999 DO - 10.1046/j.1365-2605.1999.00137.x VL - 22 IS - 1 ER -