A physical copy of the book ‘Perspectiva pictorum et architectorum’ by Andrea Pozzo is available at 2 different libraries.
The first one is:
UZH Kunsthistorisches Institut
Rämistrasse 73
8006 Zürich
Rara-Magazin Alte Signaturen (per order) IIIx 247
Reading room only
And the second one is:
ETH Library
Rämistrasse 101
8092 Zürich
Call Number: RA Rara Rar 224
No loan
Also available: an English version translated by John Sturt and John James
Call Number: RA Rara Rar 199
No loan
Online versions of the book can be found at:
https://www.e-rara.ch/zut/doi/10.3931/e-rara-4098