2002 Nissan Maxima O2 Sensors

I have a problem with the O2 sensors
in my 2002 Nissan Maxima. I have the service
engine light soon on. I went to the local Auto Zone store and the Tech pluged in a tester to
analyize the problem. It pointed to the O2 sensors.
Apearently this car has four sensors on each side
of the engine. It is hard to tell whiich is which.
Is there a way to find out which side is bank 1 sensor
1. The literature on testing an O2 sensor talks
about connecting one lead to the out side of the sensor and the other probe to the return wire. Some of these sensors have four wires. I need more
explicit information.