{HEAD ~ Such filters} are constructed as {TAIL ~ planar filters}, for instance as described in French Patent No 2 422 268, U.S. Pat Nos. 4,791,391 or 4,070,084 
are constructed as
{ HEAD ~ Such filters } are constructed as { TAIL ~ planar filters } , for instance as described in French Patent No 2 422 268 , U.S. Pat Nos . 4,791,391 or 4,070,084
HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH