Does anyone know any good, quite advanced textbooks containing the theory of simultaneous equilibria, including acid-base, complexation, solubility, etc., and how to use approximate methods to get a good, close solution for a basic problem?

e.g. With a known initial concentration of H3PO4 and NaOH, how much (volume) NaOH should I add to a 0.250 dm^{3} solution of the phosphoric acid to get a pH=7.4?

Now I solved this by hand exactly to get 0.1028588235 dm^{3} ≈ 102.86 mL, but it took me nearly half an hour. The method given in the solutions looks like it would take me 5 minutes and gets 102.84 mL as the answer.

Anyone have any recommendations?