The Effects of Active and Passive Participation in Musical Activity
(Requires University Subscription): https://www.ncbi.nlm.nih.gov/pubmed/12015810
An Introduction to the Endocrine System
https://www.khanacademy.org/science/health-and-medicine/advanced-endocrine-system#endocrine-system-introduction
An Introduction to the Nervous System
https://www.khanacademy.org/science/health-and-medicine/human-anatomy-and-physiology#nervous-system-introduction
The Difference Between Epinephrine and Acegylcholine
https://forums.studentdoctor.net/threads/epinephrine-and-acetylcholine.405197/