Design Overview of the NAIL! System. - Katherine A. Morris; Jeffrey D. Ullman; Allen Van Gelder (ICLP, 1986)

YAWN! (Yet Another Window on NAIL!). - Katherine A. Morris; Jeffrey F. Naughton; Yatin P. Saraiya; Jeffrey D. Ullman; Allen Van Gelder (IEEE Data Eng. Bull., 1987)

An Algorithm for Ordering Subgoals in NAIL! - Katherine A. Morris (PODS, 1988)

Subgoal Order for Query Optimization in Logic Databases. - Katherine A. Morris (1991)