1. Haggerty and Eley,1956
2. (1956); Nichols (1957); Le Tan Vinh;Haggerty; Eley;et al; Kredba and Bradacova (1959); Hennemanne (1960); Pinkel (1961); Finkel (1961); Krajewska,1957
3. Haggerty and Eley (1956); Kuipers and Van der Mei (1958); Celinska et al. (1961)
4. Josserand et al. (1953); Cheatham et al.
5. Haggerty and Eley (1956); Kirchhoff (1960);Josserand;Bernheim et al; Finkel,1956