Freestyle vs. Boolean: A Comparison of Partial and Exact Match Retrieval Systems. - Lee Anne H. Paris; Helen R. Tibbo (Inf. Process. Manag., 1998)

Measuring Search-Engine Quality and Query Difficulty: Ranking with Target and Freestyle. - Robert M. Losee; Lee Anne H. Paris (J. Am. Soc. Inf. Sci., 1999)