A few months back, I told you about hot to effortlessly freshen up musty books using talcum powder.  Here’s another way.  Fan the pages and lightly sprinkle with cornstarch.  Let sit overnight, then brush clean.  The absorbent powder will draw the dampness out of the porous paper, eliminating the musty odor.  Plus, the smooth powder coating will make the pages easier to turn for a more enjoyable read.