Leach, William Elford (1819). "Eleventh Room". Synopsis of the Contents of the British Museum (15th ed.). London: British Museum. pp. 63–68 [65]. Although the name of the author is not specified in the document, Leach was the Keeper of Zoology at the time.
Martin-Vivaldi, Manuel; Palomino, Jose J.; Soler, Manuel (2004). "Strophe Length in Spontaneous Songs Predicts Male Response to Playback in the Hoopoe Upupa epops". Ethology. 110 (5): 351–362. Bibcode:2004Ethol.110..351M. doi:10.1111/j.1439-0310.2004.00971.x.
Battisti, A; Bernardi, M.; Ghiraldo, C. (2000). "Predation by the hoopoe (Upupa epops) on pupae of Thaumetopoea pityocampa and the likely influence on other natural enemies". Biocontrol. 45 (3): 311–323. Bibcode:2000BioCo..45..311B. doi:10.1023/A:1009992321465. S2CID11447864.
Ibopishak, S.O. and Bimola, D.A. Comparative Study of the Treatment of Kidney Stone with Upupa epops, Cissus adanta Roxb. and Cissus javana DC* in the Urinary Medium. Published Online: July 21, 2020 ISSN: 2684-4478 DOI :10.24018/ejchem.2020.1.4.8 https://ej-chem.org/index.php/ejchem/article/download/8/6 Retrieved at 11.11 on Thursday 28/4/22.
Martin-Vivaldi, Manuel; Palomino, Jose J.; Soler, Manuel (2004). "Strophe Length in Spontaneous Songs Predicts Male Response to Playback in the Hoopoe Upupa epops". Ethology. 110 (5): 351–362. Bibcode:2004Ethol.110..351M. doi:10.1111/j.1439-0310.2004.00971.x.
Battisti, A; Bernardi, M.; Ghiraldo, C. (2000). "Predation by the hoopoe (Upupa epops) on pupae of Thaumetopoea pityocampa and the likely influence on other natural enemies". Biocontrol. 45 (3): 311–323. Bibcode:2000BioCo..45..311B. doi:10.1023/A:1009992321465. S2CID11447864.
Battisti, A; Bernardi, M.; Ghiraldo, C. (2000). "Predation by the hoopoe (Upupa epops) on pupae of Thaumetopoea pityocampa and the likely influence on other natural enemies". Biocontrol. 45 (3): 311–323. Bibcode:2000BioCo..45..311B. doi:10.1023/A:1009992321465. S2CID11447864.