1. ACT. (2019).The PreACT 8/9 Technical Bulletin. Iowa City: ACT Inc.
2. ACT and the Illinois State Board of Education. (2008).Prairie State Achievement Examination Technical Manual 2008 Testing Cycle. Iowa City: ACT Inc.
3. Colton D. A.(1995).Comparing smoothing and equating methods using small sample sizes[PhD Thesis]. University of Iowa.
4. Cui Z.(2018).Can a Machine Learn to Screen Irregularities? [ACT Data Bytes]. ACT.
5. Evaluation of Two New Smoothing Methods in Equating: The Cubic B-Spline Presmoothing Method and the Direct Presmoothing Method