$1!G.'L6!2~'^Ms - $1'Y.!5*!<@!JY'O6'JE!+5'3k!3^!Nv!JY'Yh!3^!+5!08!;O!Bd!=?!Bd!JY!+5!=_!=j!5@'JE!5*!UNs ($1!7e!<4!R;EWF!3K!JH!Nas, 1987)
Keywords: $1!5F'O=!X$!G<'L6!G*(B--$1!G.'L6s