There are different reference management apps out there, such as EndNote, Mendeley and Zotero. These apps allow you to collect, create, store, view, organise, edit and share your references with others, helping you to create your own personal and searchable library of research material overtime. You can also download, attach, view and annotate PDFs pertaining to your references. In addition, you can sync your online and desktop libraries for seamless access to your references. With the exception of Papers 3, these apps also help you write or generate your bibliography or reference list.
EndNote | Download for iOS
Price: free Devices: iPad.
Mendeley | Download for iOS | Download for Android
Price: free Devices: iPhone, iPad, iPod touch and Android.
Zotero
Zotero has no official apps for mobile devices, however, there are several third party apps you can use for your Zotero library (iOS or Android).
The mobile version of zotero.org enables you to access and edit your Zotero library on a tablet or mobile phone.
The Zotero Bookmarklet allows you to save items from your mobile device's browser directly to your zotero.org account.