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