1. A A Natale and C G Roldão, nucl-th/0204004 (2 Apr. 2002)
2. Stephan Narison, Proceedings of the Possible Existence of the Sigma Meson and its Implications to Hadron Physics, Kyoto, Japan, 2000, pp. 123–132
3. M K Volkov, A E Radzhabov and N L Russakovich, Phys. Atom. Nucl. 66, 997 (2003)
4. B D Serot and J D Walecka, Adv. Nucl. Phys. 16 1 (1986)
5. K Saito, K Tsushima, A Thomas and A Williams, Phys. Lett. B433, (1998)