TITLE: Resources for topos theory
QUESTION [10 upvotes]: I am trying to learn topos theory and I am finding a strong scarcity of resources. Is there any canonical textbook to refer someone to when learning this topic?
So far, I have only been able to find the following.

The Stacks project (Part 1, Chapter 7 gives an introduction)
"Théorie des Topos et Cohomologie Etale des Schémas" by Grothendieck, Artin and Verdier (yes, this one is quite old and in French but I have found all the necessary topics together in a better way than any other resource known to me)

In particular, I have only found a clear distinction between topology and pretopology in the second one, as well as clear guidance on how to work interchangeably between them.
Do people have any suggestions? Please list them below so other people trying to learn topos theory have a better idea of where to start!

REPLY [4 votes]: Here are some references on Steven Vickers works to look at topoi from other "geometric" and logical sides.

S. Vickers,    Locales and Toposes as Spaces Chapter 8 in  M. Aiello, I. Pratt-Hartmann and J. van Benthem (eds.), Handbook of Spatial Logics, 429–496. 2007 Springer,
S. Vickers,    Toposes pour les vraiment nuls
S. Vickers,    Sketches for arithmetic universes
S. Vickers,    Arithmetic universes and classifying toposes

I think it also worth to mention the following

I. Moerdijk,  Classifying Spaces and Classifying Topoi (surprisingly to me this one is available online as well)

For some advanced matters I also suggest to read

T. Streicher,  Fibered Categories