Once you've started using Bookends you'll want to dig deeper into its power and flexibility.
Bookends for Mac
User Guide, Tutorials
A PDF tutorial and a comprehensive User Guide for Bookends for Mac are stored on your Mac and are available from the Bookends Help menu.
How to import from Sente, EndNote, Papers, Zotero, or Mendeley
How to automate Bookends with AppleScript
How to add the Bookends Bookmarklet to your browser
Using Bookends with Hookmark (by CogSci Apps)