This figure and accompanying table and references are kindly assembled and kept up to date by Jim Lattimer. The reference of the original figure is Ultimate energy density of observable cold baryonic matter, Lattimer JM, Prakash M, Phys. Rev. Lett. 94 111101 (2005).
The most recent reference for the figure shown below is J. Lattimer, Annual Review of Nuclear and Particle Science, Vol. 62, 485, 2012.
Cite also as the following url: https://stellarcollapse.org/nsmasses and state the date at which you retrieved the data.