1. Physics in Perspective, Vol.IIB. NAS, Washington, 1973, p.1353,1360.
2. Chang K.H., Dieks D.: Ned.Tijd.Nat. 40 (1975) No.4, 28–32.
3. Chang K.H., Diets D.: Res.Pol. 5 (1976) No.4, 380–396.
4. Viesca R.de la, Alvarez-Ossorio J.R.P.: Rev.Esp.Doc.Cient.1 (1977)No.1, 57-
5. Vlachý J.: Czech.J.Phys. B28 (1978) No.12, 1409–1412.