1. American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders (5th ed.). American Psychiatric Publishing.
2. Baer, D. M. (2005). Letters to a lawyer. In W. L. Heward, T. E. Heron, N. A. Neef, S. M. Peterson, D. M. Sainato, G. Cartledge, R. Gardner III, L. D. Peterson, S. B. Hersh, & J. C. Dardig (Eds.), Focus on behavior analysis in education: Achievements, challenges, and opportunities (pp. 3–30) Merrill/Pearson.
3. Baer, D. M., Wolf, M. M., & Risley, T. R. (1968). Some current dimensions of applied behavior analysis. Journal of Applied Behavior Analysis, 1(1), 91–97. https://doi.org/10.1901/jaba.1968.1-91.
4. Barbash, S. (2012). Clear teaching: With direct instruction, Siegfried Engelmann discovered a better way of teaching. Education Consumers Foundation
5. Bereiter, C., & Engelmann, S. (1966). Observations on the use of direct instruction with young disadvantaged children. Journal of School Psychology, 4(3), 55–62. https://doi.org/10.1016/0022-4405(66)90008-2.