Amazon.com: Logitech Unifying Receiver, 2.4 GHz Wireless Technology, USB Plug Compatible with all Logitech Unifying Devices like Wireless Mouse and Keyboard, PC / Mac / Laptop - Black : Electronics
Logitech Keyboard K520 Lot Of 2 & (1) K540e Keyboard No Mouse No Receivers | eBay
User manual Logitech MK520 (English - 132 pages)
Logitech K520 Wireless Keyboard (NO RECEIVER / NO Dongle) Keyboard Only 97855066718 | eBay
Logitech Keyboard K520 Lot Of 2 & (1) K540e Keyboard No Mouse No Receivers | eBay
SOLVED] Logitech K520 keyboard not working | Quickly & Easily! - Driver Easy