See my answer here for the rationale behind this policy
Note that this will require some community members to commit to curating the resource recommendations by flagging for post notice addition, flagging+commenting on bad answers, etc. This can't go through unless we get enough people who are willing to patrol for resource recommendation questions and spruce them up to fit policy. If you wish to help, just say so in a comment below this answer.
I am using the word "resource" instead of "book" here, as this policy can apply to requests for websites as well. Note that reference requests are different, these usually have one or two answers.
What is a resource recommendation question?
A resource recommendation question is one that asks for a resource (which can be a book, website, or other resource) to learn a topic from.
This is not the same as a reference-request, which asks for a specific paper in which a derivation or concept is explained.
What sort of resource recommendation questions are allowed here?
Resource recommendations must ask for descriptive answers. It's not enough to ask for a list of books that cover topic X — a simple Amazon search can provide that.
Instead, you should ask for recommendations, which specify:
- What the book covers
- How it covers it — is it rigorous? Intuitive? How is the writer's style?
- What are the prerequisites?
and similar questions.
Actually, this becomes more of a constraint on answers to resource recommendation questions, which brings us to the next point:
How should I answer a resource recommendation question?
If you wish to answer a resource recommendation question, the answer should be substantive, and give as much information about the book as possible. Try to explain the style of the author, as well as listing the topics it covers well and the topics which it isn't so thorough with. Try to list the prerequisites too.
Here are some examples that show what good answers to resource recommendation questions should look like:
As a community member, how should I treat resource recommendations?
If you see a rather narrow resource recommendation, see if you can convert it into a question about the concept the OP really wants to know, rather than a request for resources that explain the concept.
Such questions are much more useful to the OP and the site in general, because the explanation is on-site and the reader need not go elsewhere to learn. So, if a resource recommendation looks directly answerable with a reasonable-length answer, then convert it to such a question.
Otherwise, flag the post for moderator attention asking for the resource recommendation post notice to be applied. Here's the text of the post notice:
Before answering, please see our policy on resource recommendation questions. Please write substantial answers that detail the style, content, and prerequisites of the book, paper or other resource. Explain the nature of the resource so that readers can decide which one is best suited for them rather than relying on the opinions of others. Answers containing only a reference to a book or paper will be removed!
And finally, if you see answers which are just suggestions of a book or paper without explanation, flag them so they can be deleted.
Dealing with old recommendation posts
If you come across an old recommendation post, move all of the answers that are against policy into a community wiki list answer, and give it the following banner:
This answer contains some additional resources that may be useful. Please note that answers which simply list resources but provide no details are strongly discouraged by the site's policy on resource recommendation questions. This answer is left here to contain additional links that do not yet have commentary.
This answer contains some additional resources that may be useful. **Please note that answers which simply list resources but provide no details are strongly discouraged by [the site's policy on resource recommendation questions](http://meta.physics.stackexchange.com/questions/4697/are-resource-recommendations-allowed)**. This answer is left here to contain additional links that do not yet have commentary.