I tried using Microsoft's wireless keyboard & mouse "Wedge Mobile Keyboard" and "Wedge Touch Mouse" which is compatible with tablets and smartphones - GIGAZINE
Amazon.com: Microsoft Wedge Mobile Keyboard : Electronics
Microsoft PL2 Wedge Mobile Keyboard U6R-00001 Bluetooth Wireless Keyboard - Newegg.com
Microsoft Wedge Mobile Keyboard (U6R-00001) (Non-Retail Packaging) - Walmart.com