The basic reference for Gibbs measures and phase transition is Georgii's book. It covers a lot of topics on the subject. Other good (book) references are Velenik and Friedli's book and Sinai's book. These, however, are not totally dedicated to Gibbs measures, also covering various statistical mechanics topics.
There are other lecture notes that are very helpful and well-written. For instance I can cite Arnaud's text, Anton Bovier's text (which has a part II also avaiable) and R. Fernández's text.