Address for correspondence:

Prof. S.P. Kruchinin
Bogolyubov Institute for Theoretical Physics,
Metrologichna Str. 14-b,
03680, Kiev, Ukraine,
Fax: +380 44 526-59-98
Phone: +380 44 521-31-62
e-mails: sergeikruchinin@yahoo.com
skruchin@i.com.ua