Integrated spectra of SPT0103−45 (top panel), SPT2147−50 (middle panel) and SPT2357−51 (lower panel). The black solid line is the spectrum extracted from the ALMA observations (see Sect. 2.3). The light grey line is the APEX/SEPIA spectrum (see Sect. 2.1). Red and blue vertical dashed lines indicate the position of CO(7−6) and [CI](2−1) lines, respectively, at the reference redshift of the source. The yellow and cyan shaded areas show the integration windows used to compute integrated fluxes of the CO(7−6) and [CI](2−1) lines, respectively (see Sect. 4.3). The zero-velocity corresponds to the observed frequency of CO(7−6) line for each of the sources.