$1!@g!N0'1O!M"!35'=e'F)!C[s - $1!5@'JE'Yh(B. $1'a,!UJ'Y.s ($1!0-!L,!N#'Y<!3K!JH!Nas, 1988)
Keywords: $1!G*K7o'2F'X<s