*[http://ads.harvard.edu/books/1989fsa..book/AbookC15.pdf Breakdown of Local Thermodynamic Equilibrium] George W. Collins, The Fundamentals of Stellar Astrophysics, Chapter 15 | *[http://ads.harvard.edu/books/1989fsa..book/AbookC15.pdf Breakdown of Local Thermodynamic Equilibrium] George W. Collins, The Fundamentals of Stellar Astrophysics, Chapter 15 |