I absolutely love this service and have downloaded the books and uploaded and synced them on my Google Books iOS app. Some books I'd like to recommend: Meditations, Dialogues,
The Enchiridion, Discourses, and Siddhartha.
https://standardebooks.org/ebooks/hermann-hesse/siddhartha/g...
Edit: I thought you meant "recommend to add" vs. "these are available and I recommend them", my mistake.