I also use Hyaluronic acid and natural and organic rose hip seed oil (organic retinol) in my serum and its awesome. The extremely wonderful l-ascorbic is so g=hard to find domestically. I got 90g for 27 USD (shipping and delivery and all) bit pricey nonetheless it goes a long way. https://bookmarknap.com/story4497150/how-make-vitamin-c-serum-from-orange-peel-can-save-you-time-stress-and-money