Revised integrated radio continuum spectra for the 14 SNRs in the VLSSr sample. In each spectrum the red filled circle indicates the new 74 MHz VLSSr flux density measurements, and the yellow ones the new GLEAM measurements. The remaining values are taken from the literature and plotted in blue or green depending on whethera single power law or a power law with a low-frequency turnover model was used to fit the data (see text for details). The solid line represents the best-fitting curve to the weighted data. Measurements were adjusted to the absolute flux density scale of Perley & Butler (2017). Gray-shaded bands represent the 1 and 2σ statistical uncertainty in the best-fit values of the spectral index α and the free-free optical depth τ₇₄ (indicated in the lower portion of each panel, see also Table 3).