Links to the above articles:

https://www.tandfonline.com/doi/abs/10.3109/13651501.2013.81...

https://journals.lww.com/psychopharmacology/Citation/2017/02...

https://www.frontiersin.org/articles/10.3389/fphar.2017.0028...

Also, more articles relating to lavender oil preparation and treatment of anxiety:

https://www.ncbi.nlm.nih.gov/pubmed/20512042

https://www.ncbi.nlm.nih.gov/pubmed/24456909