
Sorry, my news reader doesn't want to reply.

1) Ling, S.C. "Fluxgate magetometer for Space Application", IEEE Journal 
Spacecraft, Vol. 1, No. 2, March-April 1964, pp 175-180.

Oldish, but usable. Background information

2) "Fluxgate magnetometry", Electronics world + Wireless world, September 
1991, pp. 726-732.

Great! Circuit diagrams etc for building an electronuc compass