"Access card" for textbook?
Hello! Quick question, for the math 3a textbook it says Calc F/biol & Med (3rd) W/ Access Crd. I just copied down the ISBN real quick, found it cheapish online, and bought it. I don't see any sign of an "access card" whatever that is.
Anyways, does anyone know what it is? Is it essential for the class? And if so, can I buy it separately from the textbook? Thanks!