What are the ten courses of action (kamma)? In the Visuddhimagga, on the topic of virtue, there is a reference to the ten courses of action (kamma):


  Furthermore, virtue as volition is the seven volitions [that accompany
  the first seven] of the [ten] courses of action (kamma) in one who
  abandons the killing of living things, and so on. Virtue as
  consciousness-concomitant is the [three remaining] states consisting
  of non-covetousness, non-ill will, and right view, stated in the way
  beginning, “Abandoning covetousness, he dwells with a mind free from
  covetousness” (D I 71).


I know the quote is taken out of context from the chapter, but I was just wondering about the ten courses of action (kamma), and their reference and significance?
1. What are the ten courses of action &amp; their significance?

They are unwholesome and wholesome behaviors that lead people to live unhappily or happily now &amp; in the future.  

Unwholesome Course
Bodily Conduct
1. Killing &amp; harming living beings.
2. Taking what is not given.
3. Sexual misconduct.
Verbal Conduct
4. Lying.
5. Slandering.
6. Harsh talk.
7. Useless Idle chattering.
Mental Conduct
8. Covetous thinking.
9. Hateful thinking.
10. Seeing distortedly with wrong view.  

Wholesome Course
Bodily Conduct
1. Abandoning killing &amp; harming living beings.
2. Abandoning taking what is not given.
3. Abandoning sexual misconduct.
Verbal Conduct
4. Abandoning lying.
5. Abandoning slandering.
6. Abandoning harsh talk.
7. Abandoning useless idle chattering.
Mental Conduct
8. Abandoning covetous thinking.
9. Abandoning hateful thinking.
10. Seeing undistortedly with right view.
(You can find details about them in the references provided below.)  

2. What are their references?

You can find them in many discourses throughout the Pāḷi Canon, specially in the 10th book of the Numerical Discourses (Aṅguttara Nikāya).  

Two examples are: AN 10.176, Cunda (Cunda-suttaṃ) &amp; MN 41, Brahmans of Sala (Sāleyyaka-suttaṃ).