Reference Base Concentrations of faecal immunoreactive progestagen metab...
Schwarzenberger, F.; Francke, R.; Goeltenboth, R., 1993. Concentrations of faecal immunoreactive progestagen metabolites during the oestrous cycle and pregnancy in the black rhinoceros (Diceros bicornis michaeli). Journal of Reproduction and Fertility 98: 285-291, figs. 1-4