are original reports of research. In the sciences, these are published in peer-reviewed journals. Examples of primary sources include: Conference papers, dissertations, interviews, laboratory notebooks, patents, a study reported in a journal article, a survey reported in a journal article, and technical reports. You may see terms such as trial, study,or report.
Mohammadzaheri, F., Koegel, L., Rezaei, M., & Bakhshi, E. (2015). A Randomized Clinical Trial Comparison Between Pivotal Response Treatment (PRT) and Adult-Driven Applied Behavior Analysis (ABA) Intervention on Disruptive Behaviors in Public School Children with Autism. Journal Of Autism & Developmental Disorders, 45(9), 2899-2907. doi:10.1007/s10803-015-2451-4
are critiques, descriptions or reviews of original works. There are two types of secondary sources. The first type, review articles, are found in peer-reviewed journals. While they collect primary research, they are not creating original research. The second type includes books, magazine, or newspaper articles summarizing and simplifying the primary research.
Roy, A., Roy, M., & Deb, S. (2015). Are opioid antagonists effective in attenuating the core symptoms of autism spectrum conditions in children: a systematic review. Journal Of Intellectual Disability Research, 59(4), 293-306. doi:10.1111/jir.1212
Deffner, E. (2013). Responding to Autism: The Do's and Don'ts. Vibrant Life, 29(5), 36-39.