https://www.ncbi.nlm.nih.gov/pubmed/

Lisa WheelerGo to PUB MED. That is through the national center for biotechnology through the national library of medicine. But just type in PubMed.
Any journal article national or international that has been published in a refereed journal will be accessible (at the very least the abstract).
For what you are doing I would do equine assisted learning AND...
Then Equine Facilitated Learning AND ...
Then Equine Utilized Learning AND...
There are multiple terms for equine use learning and you have to play with those terms.