Comparison of bolometric luminosities derived using different calibrations of M_V with those derived for the same discrete MK spectral types and luminosity classes using integrated fluxes that are identified here with log L(λ₁,D) /L_⊙ (red lines). The identifications are dJM (de Jager & Nieuwenhuijzen 1987), DDS (Deutschman et al. 1976), SK (Aller et al. 1982), and W (Wegner 2006). The blocks a), b), and c) are for average MK luminosity classes V, IV, and III, respectively.