General information about collagens

The prevalence of collagen in our tissues: https://www.peptan.com/collagen-in-our-bodies/

On the 3-dimensional structure of collagen: https://pdb101.rcsb.org/motm/4

Effects of age-related collagen depletion: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1606623/

What is the role of collagen in our body? https://www.healthline.com/nutrition/collagen