While the parallel resonators P1 and P2 in the above illustrated embodiment are square devices that utilize a contour vibration mode, they may alternatively be rectangular devices like {HEAD ~ series resonators S1} and S2 that utilize {TAIL ~ a longitudinal vibration mode} 
While the parallel resonators P1 and P2 in the above illustrated embodiment are square devices that utilize a contour vibration mode , they may alternatively be rectangular devices like { HEAD ~ series resonators S1 } and S2 that utilize { TAIL ~ a longitudinal vibration mode }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL