Imidazo[1,5-a]pyrimidine and benzo[4,5]imidazo[1,2-a]pyrimidine derivatives as calcium antagonists - Alajarin, R.; Vaquero, J.J.; Alvarez-Builla, J.; de Casa-Juana, M.F.; Sunkel, C.; Priego, J.G.; Gomez-Sal, P.; Torres, R. (Bioorganic and Medicinal Chemistry, 1994)