See sections 4.2 and 5.2 of the GSL for the graphic and text you must include in/on your product. See sections 4.2 and 5.3 for the graphic and text you must include in advertisements of your product.Do you have to include the GSL in your product. I couldn't find reference in the license.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.