To identify books and other resources that accessible online, search the library catalog and look for the option to limit results to "full access online":
If you would like to send a link to a specific e-book for your students to access, please do not attempt to copy the address from the URL bar of your browser. To reliably return to a specific item, you will need to get the permalink:
On the library catalog page, look for options under "View Online". If multiple options are listed for full text available online, select whichever link you prefer.