$1'_P!={!M"'F)!C[s - $1!>'!Hk'Q[!UNs ($1'Qc'X`!3K!JH!Nas, 1970)
Keywords: $1!04K7o'KG!0s!5=(B; $1!FMK7o!5=(B--1970$1!<e!0ss