Stelios M. Potirakis Giorgos E. Alexakis George S. Tombras An alternative two-port feedback analysis approach. 156-159 1996 ICECS https://doi.org/10.1109/ICECS.1996.582737 conf/icecsys/1996 db/conf/icecsys/icecsys1996.html#PotirakisAT96a