Superconducting order parameter in NbSe$_{2}$ derived from the specific heat

To resolve the discrepancies on the superconducting order parameter of quasi-2D NbSe$_{2}$, the comprehensive specific heat measurements have been carried out.The thermodynamic consistence requires more than one energy scale of the order parameters The zero field data and the results of the mixed states respectively with $H$//$c$ and $H\bot c$ conclude: (1) $\Delta _{L}$=1.26 meV and $\Delta _{S}$=0.73 meV; (2) $N_{Se}$(0)/$ N$(0)=11{\%}$\sim $20{\%}; (3) $\Delta _{S}$ is 3-D and like on the Se derived Fermi surface. This present scenario largely removes the dispute over the order parameter existing in the previous literature. The alternative anisotropic$ s$-wave model is also discussed.