1. Bradley J W. Distribution-free statistical test. Prentice-Hall, London 1968; 68–86
2. Henningsson G, Isberg A. Multidisciplinary management of cleft lip and palate: oronasal fistulas and speech production, J Bardach, H Morris. WB Saunders, Philadelphia 1990; 787–792
3. Primary Veloplasty or Primary Palatoplasty
4. Johanson B, Lilja J, Friede H, Möller M. Early treatment of cleft lip and palate: the evolution of the therapeutic approach to cleft lip and palate in Gothenburg, M Hotz, W Gnoinski, M Perko, et al. Hans Huber Publishers, Toronto 1986; 85–89