Seasonal effect on chemical composition and biological activities of Sonoran propolis - Valencia, D; Alday, E; Robles-Zepeda, R; Garibay-Escobar, A; Galvez-Ruiz, J C; Salas-Reyes, M; Jiménez-Estrada, M; Velazquez-Contreras, E; Hernandez, J; Velazquez, C (Food Chem, 2012)