The United States Pharmacopeia and the National Formulary (USP–NF) is a combined volume of public pharmacopeial standards. USP 44 represents the forty-fourth revision of this essential text. It contains legally recognized standards for:

USP provides free sample monographs on its website. While you won’t get the entire book, you can download individual chapters relevant to your work without violating copyright.

USP offers a option for as low as $295/year for single users (depending on promotions). While not free, this is much cheaper than the print edition and includes USP 44 as part of the archive.