Pollination and plant protection in seed production of lucerne (Medicago sativa L.) Ptacek, V.; Rotrekl, J. Proceedings of the Fourth International Symposium on the Harmonization of Methods for Testing the Toxicity of Pesticides to Bees, May 15-18, 1990, Rez near Prague, Czechoslovakia: 125-130 1990 https://eurekamag.com/research/002/188/002188253.php