1. E. G. Ekdale, A. Berta, T. A. Deméré, "PLOS ONE." 6, "The comparative osteology of the petrotympanic complex (ear region) of extant baleen whales (Cetacea: Mysticeti)." e21311 (2011)
2. F. C. Fraser and P. E. Purves "Bulletin of the British Museum of Natural History (Zoology)." 7, "Hearing in cetaceans: evolution of the accessory air sacs and the structure of the outer and middle ear in recent cetaceans." 1 (1960)
3. M. Oishi, "Japan Cetology." 9, "Comparison of the cranial elements around the sub-temporal fossae of balaenopterid whales." 41 (1999)
4. Y. Okazaki, "Nature Study (News letter from the Osaka Museum of Natural History)." 21, "Discovery of sperm whale bones in Higashi Osaka City." 143 (1975)
5. H. Omura, "Scientific Reports of the Whales Research Institute." 18, "A systematic study of the hyoid bones in the baleen whales." 149 (1964)