"Coupon for Special Offer Number One." This coupon converts your term subscription to Numerical Recipes Electronic into a lifetime* subscription. Here's how:

Step 1. Cut the coupon out of the back of your Numerical Recipes Third Edition book. It must be "Coupon for Special Offer Number One". No other coupon, and no photocopy, can be accepted for this offer.

Step 2. Fill out the coupon using the same information you used when you subscribed to Numerical Recipes Electronic. The most important piece of information is your unique subscription key (two groups of 6 characters separated by a dash), which you enter as the "special offer code". (Your key was sent to you by email when you subscribed. It is NOT the number shown in the picture at the right!) If your subscription key is correct, your subscription can be upgraded. If it is not correct, the other information on the coupon will be used to try to contact you.

Step 3. Mail to

NR Coupon Center
P.O. Box 133
Bedford, MA 01730-0133
USA

Be sure to put on the correct postage. The post office will not deliver mail without the correct postage. Allow 4-6 weeks for processing, then log into your control panel at http://nrbook.com under Information for Subscribers. Instead of an expiration date, you should see the word "lifetime".