I have also found Wikipedia to be a convenient math reference, but it is not always the "best" that is easily available on the internet. If I'm looking at a top

I have also found Wikipedia to be a convenient math reference, but it is not always the "best" that is easily available on the internet. If I'm looking at a topic, it's usually fruitful to Google "introduction to X theory" and go through a few possibilities to find a literature review. Often there is a review which is a good "companion" to the Wikipedia article in terms of explanation, since the style will be different and you get some breadth of perspective. >that that's attributable to math being hard (an easily underestimated property of mathematics)