TY - BOOK ID - 138141106 TI - Item response model with internal restrictions on item difficulty AU - Butter, René.. AU - De Boeck, Paul AU - Verhelst, Norman PY - 1993 PB - Leuven KUL. Department of psychology. Research group on quantitative methods DB - UniCat UR - https://www.unicat.be/uniCat?func=search&query=sysid:138141106 AB - ER -