Review of Reviews 2008. Extensive review going back to 1964 that covered every review of inclusion versus segregation to that point. No study was found where the outcomes of segregation were better than inclusion.
Matched groups comparison. Results indicated that students in the general education classrooms had a significant, large effect size as compared with their pairs in separate classrooms on several variables. In addition, students in the general education classrooms demonstrated highly significant levels of progress as compared with the students in separate classrooms. https://journals.sagepub.com/doi/abs/10.1177/1540796920943469#articleCitationDownloadContainer
Further examples. Links to further examples as well as a huge amount of useful information for teachers and families can be found at the website of allmeansall (www.allmeansall.org.au). Research information at https://allmeansall.org.au/for-educators/