As we already had a number of questions that ask for recommendations or some off-site resources which are deemed as being off-topic for our site, I'd like to suggest the addition of a predefined off-topic close vote reason for this type of questions.
The wording could be similar to existing reasons on other sites like Startups SE or Stack Overflow:
Questions asking us to recommend or find a book, tool, software, tutorial or other off-site resource are off-topic for Computer Graphics as they tend to attract opinionated answers and spam. Instead, describe your problem or need and the steps, if any, you've taken to solve it.
What do you think about this? I'd like to have opinions from the community on whether or not to add such a reason and - if so - what the exact wording should be.