Download a free copy of VITAMIN D3 and the Great Biology Reset, by Professor David Anderson and Dr David Grimes. https://dgreatbiologyreset.com/#download
Dr Grime’s book to introduce the importance of vitamin D https://yorkbookshop.com/health-and-personal-development/307-vitamin-d-deficiency-and-covid-19-its-central-role-in-a-world-pandemic.html