Raspberry Pi doesn't come with a Bluetooth module in its board, so if you want to work with Bluetooth stacks, you should attach a Bluetooth module. The easier approach to attach a Bluetooth module into a Raspberry Pi board is to use Bluetooth USBs. There are many Bluetooth USB devices.
However, some Bluetooth USB devices are only compatible with Raspberry Pi. The following is a list of the tested Bluetooth USBs:
Bluetooth 4.0 USB Module (v2.1 Back-Compatible), http://www.adafruit.com/products/1327
JBtek, http://www.amazon.com/JBtek-Raspberry-Bluetooth-4-0-adapter/dp/B00L08NCPQ/
Black Bluetooth CSR 4.0, http://www.amazon.com/Black-Bluetooth-Dongle-Adapter-Raspberry/dp/B010LOY438/
Pluggable USB Bluetooth 4, http://www.amazon.com/Plugable-Bluetooth-Adapter-Raspberry-Compatible/dp/B009ZIILLI/
USB BLE Link, http://www.dfrobot.com/index.php?route=product/product&product_id=1220