1. Improved bandwidth of microstrip antennas using parasitic elements
2. Penard, E., and Daniel, J.P.: Electric and magnetic currents in microstrip antenna theory, Albulquerque, New Mexico p. 1982
3. PENARD, E., and DANIEL, J.P.: ‘Calcul du rayonnement d'antennes microstrip: deux exemples’. Journees Nationale Micro-ondes de Toulouse, 1981