Properties of our sample of galaxies. The panels show the normalized histograms of the distances to our galaxies in Mpc (panel a), rotation velocities V_rot in km s⁻¹ (panel b), spectroscopic stellar masses M_sp in solar units (panel c), luminosities L_B in solar units (panel d), optical radii R₂₅ in kpc (panel e), inclination angles i in degrees (panel f), central (intersect) oxygen abundances 12 + log(O/H)₀ (solid line) and oxygen abundances at the optical radii 12 + log(O/H)_R25 (dashed line) (panel g), number of points in the velocity map (solid line), and number of points used in the determination of the final rotation curve (dashed line) (panel h).