The essentials

Getting started with Cybersource essentials (PDF) (HTML)
Creating and using security keys (PDF) (HTML)
Simple order API release notes (PDF) (HTML)

Integration

Batch submission user guide (PDF) (HTML)
Card-present transactions supplement (PDF) (HTML)
Credit card services user's guide (PDF) (HTML)
Electronic check services user's guide (PDF) (HTML)
Level II and level III transactions supplement (PDF) (HTML)
Merchant descriptors user guide (PDF) (HTML)
Recurring billing with the business center (PDF) (HTML)
Recurring billing with the simple order API (PDF) (HTML)
Reporting user guide (PDF) (HTML)