WWVB NIST Radio Time Receiver Kit - WRL-10060 - SparkFun Electronics
ALANO DCF77 77kHz NIST Radio Controlled Clock Modules, 30dB High Gain Atomic Clock Receiver Module, 100mm Antenna 1.2 to 5V Operating Voltage for Radio/Radio Alarm Clock/Timer: Amazon.co.uk: Electronics & Photo
CANADUINO® 60kHz WWVB Atomic Clock Receiver - Compatible with MSF and JJY60: Amazon.com: Industrial & Scientific
Is That an Atomic Clock in Your Pocket?
The PC-board atomic clock, Part 1: Primary and secondary standards
CANADUINO DCF77 Atomic Clock Receiver Module 77.5kHz for Europe : Amazon.co.uk: Fashion
Miniature Atomic Clock (MAC - SA5X) is only 2 x 2" - Electronics-Lab.com