Main text book:
John Burgess, Philosophical Logic (Princeton University Press, 2009).
Articles/book excerpts:
Shapiro, "Classical Logic", Stanford Encyclopedia of Philosophy
Shapiro, Foundations Without Foundationalism, chapter 3 (bit.ly/18gcOoV)
Shapiro, Foundations Without Foundationalism, section 9.1.1. (bit.ly/19feS1B)
Linnebo, "Classical Logic", xx1,2
Ben Yami 2009 §§1,2
Boolos 1975, pp 509 {518
Lowe, A Survey of Metaphysics, pp. 307-12 and 319-21
Lewis, A Plurality of Worlds, pp. 1-20
Quine, Pursuit of Truth, pp. 73-4
Quine, Pilosophy of Logic, pp 64-68
Lewis, Counterfactuals, pp. 1-19 and 31-36
van Atten, On Brouwer, ch. 2
Beall, Jc and Glanzberg, Michael, "Liar Paradox", The Stanford Encyclopedia of Philosophy (Spring 2013 Edition)
As additional reading Graham Priest's Introduction to Non-Classical Logic may be found helpful, however this is not a part of the obligatory readings.