Try to look for signal flow in the schematic. The inputs send signals thru the input impedances to the op-amp. The op-amp output sends a feedback signal thru Zf to the inverting input. Signal flow ...

The SFG is a simple circuit description that many understand. It only shows input to output signal flow. The example included a series resonant circuit, Z2, that disappeared in the SFG. Z2 is included ...