Implementation of an unshielded SQUID as a geomagnetic sensor. - Lucas J. Janse van Vuuren; Anton Kilian; Temwani-Joshua Phiri; Coenrad J. Fourie; Elisabeth Pozzo di Borgo; Pascal Febvre; Elda F. Saunderson; Emile T. Lochner; Daniel J. Gouws (AFRICON, 2013)