Kim, C.w.; Chin, F.p.s.; Garg, H.K. (2006). "Multiple Frequencies for Accuracy Improvement in Near Field Electromagnetic Ranging (NFER)". 2006 IEEE 17th International Symposium on Personal, Indoor and Mobile Radio Communications. pp. 1–5. doi:10.1109/PIMRC.2006.254050. ISBN1-4244-0329-4. S2CID5420485.
Kim, C.w.; Chin, F.p.s.; Garg, H.K. (2006). "Multiple Frequencies for Accuracy Improvement in Near Field Electromagnetic Ranging (NFER)". 2006 IEEE 17th International Symposium on Personal, Indoor and Mobile Radio Communications. pp. 1–5. doi:10.1109/PIMRC.2006.254050. ISBN1-4244-0329-4. S2CID5420485.