This is definitely not the best approach. But when I am way out of my depth, the first place I look is at degree requirements for that area of expertise (from looking at a couple university websites) and then I find the textbooks used in those courses or searching online under those subject areas to get closer to the information I am actually looking for.

One of the biggest problems in learning something radically different is knowing what it is you don't know. A solid background will give you plenty of hints, and just looking at tables of contents can help you quickly get to the good stuff if you aren't looking for a solid background.