Rest-frame optical-UV SED of the three sources discussed in this work. The best-fit AD models derived for each target are reported as a black solid line (η_d ∼ 0.1) and a grey dashed line (η_d ∼ 0.3). During the fit, we only considered photometric data points (filled circles) not affected by IGM absorption (shaded area in yellow) and we did not use data affected, even marginally, by such absorption (white circles).