$1'=e!Rm-b~'Xm'L4!3"'YF'XZ'XL(B. $1!0&s - $1!K3!=T!+5'_#(pe!Oz'YF'XLs ($1!bf'c+!Fd!0d!FM!3K!JH!Nas, 1988)
Keywords: $1!;E'Xi(B--$1'Oy'X<(B; $1'L4'Rqs