research Exogen hair characterization in human scalp 35 citations , March 2007 in “Skin Research and Technology” The conclusion is that exogen is a unique hair cycle phase and the new sampling method specifically targets this stage, which may help in future hair loss research.
research Physical and mechanical properties of the hair shaft: A review of measurement techniques to verify the efficacy of cosmetic products January 2024 in “Seven Editora eBooks” Different techniques measure hair properties to ensure cosmetic products work.