Morgenstern, Barry . "A Comparison of High and Low Frequency Criteria on Reading Agility, Retention, Endurance and Direct Instruction Reading Mastery Checkout Performance of Elementary Students Academically At-Risk." Doctoral dissertation, Ohio State University, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=osu1392387051Chicago Manual of Style (17th edition)