When doing Research, check the comprehensive database of literature from PubMed.

NIH is the nation’s medical research agency – supporting scientific studies that turn discovery into health.

There are detailed instructions for searching Using PubMed with the “PubMed Quick Start Guide”  For specific references to Autism, in the search bar, type in Autism and then the word(s) you are searching for.  For example, Autism Gastrointestinal.