1. (2) A. Miura : “A study of some problems about breastfeeding and support for breastfeeding mothers”, The Faculty journal of Komazawa Women's University, Vol. 21, No. 21, pp. 325-335 (2014) (in Japanese)
2. (3) E. Kashiwabara and E. Mori : “Maternal difficulties with breastfeeding behavior”, Japan Society of Maternal Health, Vol. 52, No. 2, pp. 270-277 (2011) (in Japanese)
3. (4) E. Kashiwabara and E. Mori : “Relationship between maternally perceived difficulties with breastfeeding and objective neonatal breastfeeding behavior”, Japan Society of Maternal Health, Vol. 52, No. 2, pp. 278-285 (2011) (in Japanese)
4. (5) J. F. Bosma, L. G. Hepburn, S. D. Josell, and K. Baker : “Ultrasound demonstration of tongue motions during suckle feeding”, Developmental Medicine & Child Neurology, Vol. 32, No. 3, pp. 223-229 (1990)
5. (6) A. J. Nowak, W. L. Smith, and A. Erenberg : “Imaging evaluation of artificial nipples during bottle feeding”, Arch Pediatr Adolesc Med, Vol. 148, No. 1, pp. 40-42 (1994)