Here are the articles I referenced.
10 best essential oils and how to use them | Well+Good
Changes in 5-hydroxytryptamine and cortisol plasma levels in menopausal women after inhalation of clary sage oil. - PubMed - NCBI
Topically applied Melaleuca alternifolia (tea tree) oil causes direct anti-cancer cytotoxicity in subcutaneous tumour bearing mice. - PubMed - NCBI
[Effectiveness of Oleum menthae piperitae and paracetamol in therapy of headache of the tension type]. - PubMed - NCBI
Tea Tree Oil
More Kids Accidentally Poisoned by Essential Oils