How Things Work Volumes, I to IV

Upon receipt of payment, your order is securely packaged and shipped the next business day. All orders within the United States are shipped via the United States Postal Service (USPS). For international orders, we provide Air Mail, Ground or Surface mail and Global priority shipping. Inside the United States, media (regular) mail shipping costs are: 3.50 for the first item and 1.75 each for additional items. Priority shipping (three to seven business days) costs $5.50 for the first item and an additional $4.00 per item after the first. We accept the following credit cards: VISA, MASTERCARD, AMERICAN EXPRESS, and DISCOVER. We also accept US Postal Money Orders and payments through PayPal, and the fund must be paid before shipping. Our PayPal account name is "cpk1961@yahoo.com" - Thank you for your order! We have 30 days FULL money back return policy, if not satisfied. Return your product in the same condition when it was received.