Threading Wires | Model Engineer : vimarsana.com
Threading Wires | Model Engineer
https://www.threadcheck.com/the-three-wire-method-of-measuring-pitch-diameter/technicalinfo/
https://everbright.com.tw/userdir/56 c.pdf (metric wires for Whitworth form threads)
https://dx.doi.org/10.6028/nbs.lcirc.23r1923 (old, but comprehensive)
The very best source on this is an old Van Keuren catalogue, but you have to buy a paper copy as none are online yet.
For specific thread measurements, drill blanks (available from the likes of Zoro Tools) make serviceable measuring wires. If you did not know already, ArcEuro sell a set of wires.
The special sauce words to go into Google are whitworth three wire thread measurement .