$1!0w'Ep!4$'Wl'Pt'Ep!4$(B, $1!X$!Bg!3S'Ep'Y$!5w!3S'Ep'Wl'XN![ms - $1!Co!2r!NOs ($1!7e!<4!0d!FM!3K!JH!Nas, 1987)
Keywords: $1!3S'Ep'Wl(B: $1'Wl!WKs