How do you get The 39 Clues book 10 cards?

most book stores but I know how to get free cards:

To get digital versions of the Cards included in a Card Pack, send a self addressed postage-stamped envelope with sufficient postage to: The 39 Clues Card Pack Mail In Entry for Card Pack #______ (indicate which pack you are requesting cardsfor)

Scholastic Inc.

557 Broadway

New York, NY 10012

For each entry, please make sure to include your username and the e-mail address you used during registration (your e-mail if you are 13 or older; your parent's/legal guardian's e-mail if you're under 13). You will receive back 16 unique IDs associated with a particular Card Pack, and when you enter the unique IDs online, the 16 Cards will be added to your online collection.

There is no limit to the number of mail-in requests for Cards in Card Packs, but there is a limit of one request per outer mailing envelope. Digital versions of the Cards included in Card Packs will be available only after the Card Pack is available in stores.

For mail-in requests, residents of Canada and the US states of Washington and Vermont may omit return postage.

my agent card is P44HWMW6XP