In Sardinha et al., 2020, we can find the Raman spectra of GO with different degree of oxidation (see please the article for the detailed discussion of the preparation of GO). The researchers obtained five oxidation degrees with a synthesis which is using 2.0, 2.5, 3.0, 4.0, and 5.0 g of oxidizing agent for each 1.0 g of graphite. The authors are discussing the Raman spectroscopy of carbon-based materials, considering the features that we have already seen in the literature mentioned above. "The first order reveals the domain of two characteristic D and G bands." The D band (from 1350 to 1380 cm -1 ) is giving a measure of the disorder in the crystalline structure. The G band, from 1575 to 1600 cm -1 , "is a characteristic of carbon-carbon vibration in the plane of the aromatic layers" (Sardinha et al., 2020). ). The apparent G peak is named as "Gapp". "This superposition renders the ID/IGapp ratio an unreliable measure for the reduction of GO and has prevented it from accurately describing some of the recently reported GO and rGO samples. propose that the best measure of GO reduction is the difference in the positions of the D'inf and Gapp peaks, i.e. D'inf - Gapp" . The inferred D' mode is named as "D'inf".