Botox studies :
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5782443/
https://www.ncbi.nlm.nih.gov/pubmed/21042071
scalp tension relaxer :
https://www.ncbi.nlm.nih.gov/pubmed/2365903
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5782443/
https://www.ncbi.nlm.nih.gov/pubmed/21042071
scalp tension relaxer :
https://www.ncbi.nlm.nih.gov/pubmed/2365903