Discount code is valid for one time 30% off any eBook purchase from this page. One promo code per person. Offer valid from May 24, 2013 at 12:00 AM through May 27, 2013 at 11:59 PM EST. Offer is not valid in conjunction with any other offer or promotion and cannot be used to adjust amount paid on previous purchases. Promotional code must be entered at time of purchase to qualify for this discount. Discounts cannot be applied nor the discount value refunded once a purchase is complete. We reserve the right to change or end this offer at any time without notice.