(3gPG gh GdGSdGe (B: s (3SdSI QSGFd JHMK Yf GdacQI GdGSdGejI GdMOjKI(B((3GdeLehYI GdKGfjI(B) / s ((3HjQhJ (B: s (3GdecJH GdGSdGej , s, 1979)
Keywords: (3GdOYhI hGdEQTGOs