1. National Institutes of Health. "Vitamin D." MedlinePlus, https://medlineplus.gov/vitamind.html.
2. "Vitamin D - Health Professional Fact Sheet." 18 Sep. 2023, https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/
3. Holick MF. "Vitamin D Deficiency." New England Journal of Medicine, 2007.
4. Bischoff-Ferrari HA, et al. "Estimation of optimal serum concentrations of 25-hydroxyvitamin D for multiple health outcomes." The American Journal of Clinical Nutrition, 2006
5. Strople J, et al. "Vitamin D deficiency in patients with intestinal malabsorption syndromes—think in and outside the gut." Journal of Digestive Diseases, 2015.
6. Wortsman J, et al. "Decreased bioavailability of vitamin D in obesity." The American Journal of Clinical Nutrition, 2000.
7. Heaney RP, et al. "Human serum 25-hydroxycholecalciferol response to extended oral dosing with cholecalciferol." The American Journal of Clinical Nutrition, 2003.
8. Vitamin D Council. "Vitamin D and your skin color." [Link to the Vitamin D Council's information on skin complexion and vitamin D].
9. Institute of Medicine (US) Committee to Review Dietary Reference Intakes for Vitamin D and Calcium. "Dietary Reference Intakes for Calcium and Vitamin D." National Academies Press, 2011.
10. Annweiler C, et al. "Vitamin D and cognition in older adults: international consensus guidelines." Geriatrie et Psychologie Neuropsychiatrie du Vieillissement, 2016.
11. Garland CF, et al. "Meta-analysis of all-cause mortality according to serum 25-hydroxyvitamin D." American Journal of Public Health, 2014.
12. Lerchbaum E, et al. "Vitamin D and PCOS: a systematic review and meta-analysis." European Journal of Endocrinology, 2013.
13. Faubion SS, et al. "2017 Hormone Therapy Position Statement of The North American Menopause Society." Menopause: The Journal of The North American Menopause Society, 2017.
14. Gao Q, et al. "Vitamin D and sleep disorders." Sleep Medicine, 2012.
15. Kocalevent RD, et al. "Vitamin D deficiency and health-related quality of life in chronic fatigue syndrome: a cross-sectional study." Journal of Psychosomatic Research, 2017.
16. Martineau AR, et al. "Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data." BMJ, 2017.
17. Holick MF, et al. "Evaluation, treatment, and prevention of vitamin D deficiency: an Endocrine Society clinical practice guideline." The Journal of Clinical Endocrinology & Metabolism, 2011.
18. Wacker M, Holick MF. "Sunlight and Vitamin D: A global perspective for health." Dermato-Endocrinology, 2013.
19. Kerr DC, et al. "Associations between vitamin D levels and depressive symptoms in healthy young adult women." Psychiatry Research, 2015.
20. Barker T, et al. "Vitamin D supplementation, muscle strength, and physical function in athletes." Medicine & Science in Sports & Exercise, 2013.
21. Rasheed H, et al. "Relationship between serum ferritin and vitamin D levels and hair loss among women in the central part of Iran." Skin Pharmacology and Physiology, 2013.
22. "Vitamin D - StatPearls - NCBI Bookshelf." 9 Apr. 2023, https://www.ncbi.nlm.nih.gov/books/NBK441912/
23. "Vitamin D and Breast Cancer: Latest Evidence and Future Steps." 20 Dec. 2017, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5802611/
24/ "Association between Vitamin D deficiency and Breast Cancer - PMC." https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5510119/
25. "Occupational exposure to solar ultraviolet B radiation and risk of ...." https://oem.bmj.com/content/78/4/286