$1!0&!GW!<D'8J!9%'X2s - $1-5\!\2!Oz!09'Q[s ($1!0&!GW!0d!FM!3K!JH!Nas, 1981)
Keywords: $1!04K7o'Q<'I&!7y!KH(B; $1!JU'Kz(B; $1';1'E-(B; $1!0^!\(s