The first input signal is applied to {HEAD ~ a base} or gate of {TAIL ~ the second transistor} with regard to said reference point 
of
The first input signal is applied to { HEAD ~ a base } or gate of { TAIL ~ the second transistor } with regard to said reference point
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH