Product Delivery
▸ Within 24 hours after the paper book is shipped, the system will automatically send the order link to the order mailbox
▸ PDF contains digital watermark: Buyer Name + Order ID + Timestamp
▸ Link expires: 72hrs after first access (max 3 downloads)
Usage License
Permitted: Personal study / Classroom handouts / Internal corporate training
Prohibited: Commercial redistribution / Removing watermarks / Public uploading
Technical Support
| ssue Type | Response Time | Resolution |
|---|---|---|
| Invalid link | 2 hours | Regenerate encrypted link |
| File corruption | 24 hours | Send compatible format |
| Watermark error | 48 hours | Issue correction notice |
Refund Policy
✓ Accepted: Page mismatch / Unreadable content / Technical failure
✗ Not Accepted: Completed download / Device issues / Academic disputes
Version Updates
▸ Free updates for major revisions (≥30% changes)
▸ Notifications sent to original purchase email