Books and other Products Return Policy The Chemical Heritage Foundation (CHF) does not accept returns after 180 days. Before returning books or other items to CHF, please contact our Book Sales Dept. toll free (U.S. and Canada) at 800-247-6553, or fax 419-281-6883, to obtain permission for return. Outside the U.S. and Canada, call 419-281-1802. All returned items must be in resalable condition. CHF reserves the right to change the terms of this return policy at any time but will not do so without posting the revised policy on this Web site. We encourage you to review this policy periodically and before attempting any returns.