1. 1)See,forexample,R.H.Doremus,B.W.RobertsandDavidTurnbull:Growth and Perfection of Crystal,JohnWiley&Sons,Inc.,NY,(1958),p.267.
2. 2)T.NakataoandK.Sakate:OyoButuri,40(1971),951.
3. 3)T.NakataoandK.Sakate:OyoButuri,41(1972),610.
4. 4)T.Nakatao,S.KitagawaandY.Ohta:JapanJ.Appl.Phy.,12(1973),497.
5. 5)T.NakataoandY.Ohta:JapanJ.Appl.Phy.,15(1976),243.