While a quick search for a "free download" might lead to outdated blog posts, the best way to get professional-grade information is through reputable formulation schools.
Organizations like the Society of Cosmetic Chemists often publish abstracts or white papers that are free to read for educational purposes.
Schools like Formula Botanica or School of Natural Skincare often offer free "Foundation" or "Taster" PDFs that are far better than random downloads.
The next morning, Maya’s small kitchen smelled like ozone and crushed rose petals. She had the formula. She had the "A-Z." But as she looked at her reflection in the darkened laptop screen, she noticed her eyes looked a little brighter—maybe too bright.
Sites like LibreTexts occasionally have chemistry chapters dedicated to cosmetic science.