Verboom WC. Bird vocalizations: seven different types of Great tit (Parus major) vocalizations.; 2018. Available at: https://www.researchgate.net/profile/Willem_Verboom2/publication/329390530_Bird_vocalizations_seven_different_types_of_Great_tit_Parus_major_vocalizations/links/5c1618f34585157ac1c5cbaa/Bird-vocalizations-seven-different-types-of-Great-tit-Parus-major-voc.