Equation of State and Neutron star I'm searching for equation of state books, with references to neutron star and ultra-dense matter.
 A: You don't say at what level you are studying this. Before you get stuck into the intricacies of exotic neutron star equations of state you need a good grounding in statistical mechanics and nuclear physics.
A good place to start is the first few chapters of Shapiro & Teukolsky; "White Dwarfs, Neutron Stars and Black Holes" (http://www.amazon.co.uk/Black-Holes-White-Dwarfs-Neutron/dp/0471873160), paying close attention to the sections on the cold equation of state below and above the neutron drip. Get to grips with the ideas behind (i) ideal fermion degeneracy pressure; (ii) the Harrison Wheeler equation of state; (iii) the ideal n,p,e,$\mu$ gas. This is a very authoritative text; I find it not too hard to digest - at least the parts I mention above. However, things have moved on quite a bit since it was published, particularly on the nucleon interactions in dense, many-body systems; the appearance of hyperons; pion/kaon condensation and quark matter. For these I have used a variety of sources:
I found the thesis of Martin Urbanec (2010) an excellent read (it can still be found here).
https://pdfcoffee.com/neutron-star-pdf-free.html
It covers Skyrme models, relativistic mean field models, rotating neutrons stars, strange stars, the MIT bag model, and importantly, a comparison of models with observations.
There are several reviews of the topic by John Lattimer; he is very strong on what observations can constrain. A recent, quite substantial one is Lattimer (2013).
An older, but highly cited overview is by Lattimer & Prakash (2001)
Gulminelli (2013) provides a reasonable review of progress in the EOS over the last 20 years.
I found this review by Heiselberg & Hjorth-Jensen (2000) good for a description of the EOS of asymmetric nuclear matter and the possible phase changes at high densities.
Weber et al. (2008) provide a lots of discussion about the exotica - meson condensation, hyperons, quark deconfinement and especially strange matter.
You could also look at some of the literature cited in answers to this related question: Introduction to neutron star physics
