| Source | Description | Access Model | |--------|-------------|----------------| | (official publisher) | Official digital version via e-book platform | Purchase or school license | | Google Play Books | Licensed digital Teacher’s Book | Paid download | | Amazon Kindle | Kindle edition (DRM-protected) | Paid download | | Educational Platforms (e.g., Edelweiss, VitalSource) | Institutional access | Subscription or one-time fee |