How to completely quit an app on the iPad
For iOS7 and later
http://howto.cnet.com/8301-11310_39-57602601-285/how-to-force-close-apps-on-ios-7/iOS5
For iOS6/iOS5
To do this, double-tap the home button to access the task manager. Press and hold on the unrealBook icon in the task manager until it wiggles. Then press the minus (-) sign to the left of the icon. This will quit unrealBook removing it from memory. Here is a link to a detailed explanation: