Continuum-subtracted, optical spectra of the 18 targets in the Hβ spectral range (upper panels). Abscissa is rest-frame wavelength (top scale) and radial velocity with respect to rest frame (bottom); ordinate is normalized specific flux, also in the rest frame. Thin black line: observed spectrum, thick black: broad component of Hβ; thick blue shaded cyan: full profile of [OIII]λλ4959,5007; magenta: Hβ broad blueshifted emission; grey: Hβ narrow component; pale green: Fe II template. The dashed magenta line traces the full empirical model of the spectrum. Lower panels: observed spectrum minus empirical model.