A reference can be ..
Here we can find further references. I like this about.com especially listing up the hot topics. What’s today in hot topic and give us guidance from A to Z;
I put here an example. Blogging. Blogging now one of the most popular in the world. Why that so popular, the answer can be found here. Detail in step by step. About.com has a lot of article that help you get in to blogging. Guidance for starting a blog, Tools, How to design a Blog, Marketing Blog, Blogging Jobs, Business Blogging and also How to monetize your Blog. Have a look.