Can you please enlighten us with the concept of karma? Where can we read more about this in depth?

Can you please enlighten us with the concept of karma? Where can we read more about this in depth?
Sri Sri Ravi Shankar: The real meaning of is Karma is Action. Action can be classified into three: The past, present and future. The past actions are impressions, the future actions are also impressions and present actions is Karma that is giving you result now. So, Karma means the impression of the past, which will draw similar situations in the future and that is the future Karma. And present action what you are doing is creating an impression in your mind and that is again called Karma. I will give you a simple example. How many of you have the habit of drinking coffee first thing in the morning? How many of you get a headache when you don’t drink coffee? (Many raise their hands) This is coffee Karma. Because you have been drinking coffee, it has made certain impressions in the consciousness, and if one day you don’t drink coffee, you get a headache. That is coffee Karma.