It's not the most accessible, but it's pretty interesting. Turning a problem into its dual has always been a bit of a dark art to me, but this article makes the benefits of doing so reasonably clear.
* L7 (Intro): http://timroughgarden.org/w16/l/l7.pdf
* L8 (Duality I): http://timroughgarden.org/w16/l/l8.pdf
* L9 (Duality II: http://timroughgarden.org/w16/l/l9.pdf
——
[0] https://en.m.wikipedia.org/wiki/Dual_linear_program
[1] http://www.seas.ucla.edu/~vandenbe/236C/lectures/conj.pdf slide 23 on down.
——
[0] http://web.stanford.edu/~boyd/cvxbook/bv_cvxbook.pdf#page229