Bookends is a comprehensive reference management app designed for iPad, iPhone, and iPod touch. With Bookends, you can effortlessly search and download references from popular sources like Amazon, Google Books, JSTOR, PubMed, and more. The app also allows you to organize your references into groups, annotate PDFs directly within the app, and easily email references to yourself or others.

One of the standout features of Bookends is its integration with iCloud. This enables you to sync all your libraries and attachments across iOS devices and with Bookends on your Mac. Whether you're at your desk or on the go, you'll have full access to your references and sources.

However, it's important to note that the free version of Bookends has some limitations. Searches are limited to a maximum of 20 references, you can only store 50 references in your local database, and annotated PDFs are watermarked. Additionally, ads are displayed in the app. To unlock the full functionality, you can make an in-app purchase for the Standard Version or opt for the Pro Features Yearly Subscription.

Overall, Bookends is a powerful reference management app that offers a seamless experience for researchers, students, and professionals. With its extensive search capabilities, organization features, and iCloud integration, it's a valuable tool for anyone looking to manage their references on iOS.