In their book "Feedback Amplifiers - Theory and Design" (Kluwer, 2002), Gaetano Palumbo and Salvatore Pennisi describe their circuits by making use of a generic transistor that represents BJTs, HBTs, Mosfets and Mesfets.
The generic device of a given polarity is represented by this symbol (actually two, to consider the possibility of a substrate)
and is used in conjunction with "a generic small-signal model applicable to a variety of different transistor types operating in the active region" that is this one:
This 'unified' device is introduced
"to ensure that all analytical results derived herein are applicable
to feedback configurations realised with both BJT and MOSFET
technologies –including heterostructure bipolar transistor (HBT) and
III-V compound metal-semiconductor field effect transistor (MESFET)
"is identified by four terminals denoted as X, Y, Z and B.
Specifically, X, Y, and Z respectively representing the emitter, base,
and collector terminals for BJTs (and HBTs) or the source, gate, and
drain of MOSFETs (and MESFETs). The fourth terminal B represents the
substrate or bulk node, it is almost always biased at a fixed
potential and conducts a negligible static current. Symbols X, Y and Z
were chosen to remind us of the functional equivalence between our
generic device and the negative second generation Current Conveyor"
The first appearance ought to be in the paper
G. Palumbo, J. Choma Jr.,
“An Overview of Analog Feedback Part I: Basic Theory,”
Analog Integrated Circuits and Signal Processing,
Vol. 17, No. 3, pp. 175-194, Nov. 1998.