Comparison of the 124 sources in our sample with all BL Lacs and FSRQs in the 4FGL-DR4 catalogue. Left: photon spectral index versus the integral photon flux from 1 to 100 GeV. Middle: photon spectral index versus the variability index. Right: variability index versus the integral photon flux from 1 to 100 GeV. The photon index, flux, and variability index values are from the 4FGL-DR4 catalogue. We represent all the BL Lac sources from the 4FGL-DR4 catalogue with blue circles and the FSRQs with orange circles. The sources selected for this work are marked with dark crosses, the radiogalaxy of the sample (4FGL J1518.6+0614) is marked with a red star, and the FSRQ (4FGL J0132.7–0804) is marked with a green star.