The Semantics of Reflected Proof - Stuart F. Allen; Robert L. Constable; Douglas J. Howe; William E. Aitken (LICS, 1990)

Metalogical Frameworks II: Developing a Reflected Decision Procedure. - William E. Aitken; Robert L. Constable; Judith L. Underwood (J. Autom. Reason., 1999)