Diagram of [N ii]λ6584/Hα versus [O iii]λ5007/Hβ . The symbols denote results for the measured H ii regions in our target galaxies. The solid line separates objects with H ii region spectra from those containing an AGN according to Kauffmann et al. (2003), while the dashed line represents the same separation according to the work by Kewley et al. (2001). The gray (light blue) filled circles show a large sample of emission-line SDSS galaxies from Thuan et al. (2010).