(**https://pmc.ncbi.nlm.nih.gov/articles/PMC9618501/)**
(**https://pmc.ncbi.nl.nih.gov/articles/PMC6791161/)**
(**https://pmc.ncbi.nlm.nih.gov/articles/PMC2699641/)**
(**https://jamanetwork.com/journals/jamadermatology/fullarticle/412795)**
(**https://onlinelibrary.wiley.com/doi/10.1111/jocd.13040)**
(**https://jddonline.com/articles/a-randomized-double-blind-controlled-comparative-trial-of-the-anti-aging-properties-of-non-prescr)**
(**https://smartandhandsome.in/the-role-of-retinol-for-skin/)**
(**https://wellbeingnutrition.com/blogs/weight-metabolism/collagen-vs-retinol-the-ultimate-skincare-showdown)**
(**https://www.skinceuticals.com/skincare-advice/how-to-use-retinol.html)**
(**https://www.clinikally.com/blogs/news/understanding-retinol-burn-causes-prevention-and-care)**