"Time Signal Station QSL Cards: 1984 YVTO Venezuela". http://www.swlqsl.com/TimeSignal/1984%20YVTO%20Venezuela.html
EiBi frequency list http://www.eibispace.de/dx/README.TXT
Glenn K. Nelson et al., (2005) NIST Time and Frequency Radio Stations: WWV, WWVH, and WWVB, Boulder, Colorado: National Institute of Standards and Technology, p. 107. http://tf.nist.gov/timefreq/general/pdf/1969.pdf
Meinberg radio clocks, YVTO, retrieved 2013-05-06 http://www.meinbergglobal.com/english/glossary/yvto.htm
"Time Signal Station QSL Cards: 1984 YVTO Venezuela". http://www.swlqsl.com/TimeSignal/1984%20YVTO%20Venezuela.html
March 26, 1984 2.15 a.m., YVTO 6100 Caracas, Venezuela time signal station 1 KW https://www.youtube.com/watch?v=UuzlAoz4KjE
QSL information pages: YVTO shows 5000 kHz reception in September 1990. http://www.schoechi.de/as-ven.html#YVTO