Basic references to the HSD model:

Relativistic transport approach for nucleus-nucleus collisions from SIS to SPS, W. Ehehalt and W. Cassing: ENucl. Phys. A 602 (1996) 449-486, arXiv:hep-ph/9507274.
Strangeness production in the HSD transport approach from SIS to SPS energies, J. Geiss, W. Cassing and C. Greiner: Nucl. Phys. A 644 (1998) 107-138, arXiv:nucl-th/9805012.
Hadronic and electromagnetic probes of hot and dense nuclear matter, W. Cassing and E.L. Bratkovskaya: Phys. Reports 308 (1999) 65-233.