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