Structured Operational Semantics for Concurrency and Hierarchy. - Andrew C. Uselton (STACS, 1993)

A Compositional Semantics for Statecharts using Labeled Transition Systems. - Andrew C. Uselton; Scott A. Smolka (CONCUR, 1994)

A Process Algebraic Semantics for Statecharts via State Refinement. - Andrew C. Uselton; Scott A. Smolka (PROCOMET, 1994)