Authorize.net Advanced Integration Method (AIM) Guide
Authorize.net Simple Integration Method (SIM) Guide
Authorize.net Automated Recurring Billing (ARB) Guide
Paypal Website Payments Standard Integration Guide
Paypal Website PayFlow Pro Integration Guide
Paypal Website Payments Pro Integration Guide
First Data Global Payment Gateway Connect Guide
First Data Global Connect Web Service API
QuickBooks Merchant Services Gateway Guide
National Merchants, Inc Gateway Guide