Size-luminosity relation for C IV BLR. Together with APM 08279+5255, all the objects with measurements of C IV BLR size and monochromatic luminosity at 1350 Å available in the literature have been included in this plot: NGC 4395, NGC 7469, NGC 3783, NGC 5548, and 3C 390.3 from Peterson et al. (2004, 2005), NGC 4151 from Metzroth et al. (2006), QSO 2237+0305 from Sluse et al. (2011), MACHO 13.6805.324 from Chelouche et al. (2012), S5 0836+71 from Kaspi et al. (2007), and PG 1247+267 from Perna et al. (2014), Trevese et al. (2014). Colour and symbol codes are explained in the plot. For comparison with our fit, we also report the fits performed by Peterson et al. (2005, 2006) and Kaspi et al. (2007) (see legend in the plot).