$$ \mathcal{L_{\mathrm{eff}}} = \mathcal{L}_{\pi \pi}(f_\pi,m_{\pi}) + \mathcal{L}_{\pi N}(f_{\pi},M_{N},g_A,c_i,d_i,...) + \mathcal{L}_{NN}(C_{i},\tilde{C}_{i},D_{i},...) + \ldots $$

• R. Machleidt, D. R. Entem, Phys. Rep. 503, 1 (2011)
• E. Epelbaum, H.-W. Hammer, Ulf-G. Mei\ss{}ner, Rev. Mod. Phys. 81, 1773 (2009)