References for dBm,power, and volts with respect to a 50ohms system.
Anritsu Company RF measuring equipment http://www.us.anritsu.com/downloads/files/Power_Conversion_Table.pdf
Analog Devices Company RF semiconductor http://www.analog.com/Analog_Root/static/techSupport/designTools/interactiveTools/dbconvert/dbconvert.html
Miniciruits Company RF components http://www.minicircuits.com/pages/pdfs/dg03-110.pdf
As always, double check to matchs with power formulas.
Company names above are register to that respective company.