Professor Nicolas Boccard of the Economics Department at the Universitat de Girona in Spain thinks industrial organisation is fun. So much so that he's written a text book Industrial Organization: a Contract Based approach and published it online on an open source basis. If you like the look of it you can pay for an on-demand printed copy for €9 plus shipping. I've paged through some sections and it looks an incredibly comprehensive text, with plenty of European as well as US examples, which is distinctive and useful.

As he writes, the reason for the open source route was:

In a nutshell, because I did not write my book for money but for fun.
So, once the deed is done, the cost is sunk and the only sensible course
of action is to maximize diffusion through open-sourcing.

In fact, there was money involved. Prof Boccard says:

“Money-wise, the output comes at a total cost of approximatively 200k€
to the Catalan Government, my official employer i.e., less than 3 cent
per inhabitant or 200€ per page of final product.”

And the lucky Catalans are now cross-subsidising any non-Catalan users of the book. For those who might be tempted, here is a useful diagram of the contents: