This H.-J. Appenzeller was probably the first owner of the bike.
Bikes from Pietro del Po are actually quite common in Zurich as he owned a bikeshop near the busy Langstrasse.
Often these bikes are painted in blue and white as these are the colours of the city flag.
The sticker on the shown rim says "Andy Muff"... he was a swiss racer in the 80s and nowadays he designs bicycles. You could ask him if he knows something about this bike of yours: conceptcycle[dot]ch