C# sample - how to find, connect to, and display data from supported BLE devices
Bluetooth Spec. - Service Discovery
Bluetooth Spec. - GATT Services
Bluetooth Spec. - GATT Characteristics
Bluetooth low energy Characteristics, a beginner's tutorial
Bluetooth Low Energy for Android
Bluetooth Low Energy on Android
Xamarin - Writing Responsive Applications (Multithreading)
Xamarin - Creating Android Services (better than multithreading for responsive applications)