1. http://whitespaces.spectrumbridge.com/whitespaces/home.aspx. http://whitespaces.spectrumbridge.com/whitespaces/home.aspx.
2. https://www.google.com/get/spectrumdatabase/. https://www.google.com/get/spectrumdatabase/.
3. http://sdr.osmocom.org/trac/wiki/rtl-sdr. http://sdr.osmocom.org/trac/wiki/rtl-sdr.
4. https://www.tablix.org/~avian/blog/archives/2015/03/noise_figure_measurements_of_rtl_sdr_dongles/. https://www.tablix.org/~avian/blog/archives/2015/03/noise_figure_measurements_of_rtl_sdr_dongles/.
5. https://www.msoon.com/LabEquipment/PowerMonitor/. https://www.msoon.com/LabEquipment/PowerMonitor/.