Transistor 168 has {HEAD ~ its emitter} coupled to low voltage source A via {TAIL ~ resistor} 170, the combination of which forms a current source 
coupled via
Transistor 168 has { HEAD ~ its emitter } coupled to low voltage source A via { TAIL ~ resistor } 170 , the combination of which forms a current source
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH