The authors thank the authoritieso f the Czechoslovaka nd Hungarian Academieso f Sciencesf or the opportunityto cooperateT. he authorsa re also indebtedto ProfessorE . Nagy and Dr. I. C. SzGp for their interests;
upporta nd helpfuld iscussionosn this topic.T het echnicaal ssistancoef Cs. Farkasis gratefully acknowledged;