Two good book-length treatments of superscalar design are [SHEN05] and [OMON99]. Worthwhile survey articles on the subject are [SMIT95] and [SIMA97]. [JOUP89a] examines instruction-level parallelism, looks at various techniques for maximizing parallelism, and compares superscalar and superpipelined approaches using simulation. Recent papers that
provide good coverage of superscalar design issues include [SIMA04], [PATT01], and [MOSH01].