I can confirm
LSS = 38.95 x SQR (temp Kelvin)
or
LSS = 38.95 x SQR (temp C + 273)
LSS = Local speed of sound (KTAS). Multiply by desired Mach number to get the appropriate TAS.
I can recommend "Air Data Conversion" programme, should be available on
http://www.avionic-cbt.co.uk/adc/adcsetup.exe but it does not work right now? It is a 30-day trial version.
Edited for an "oops" ...