Peak spectral radio luminosity vs. the product of the time of the peak and the frequency of the measurement for supernovae of Types Ib/c and IIb. The observed supernovae are designated by the last two digits of the year and letter(s). References to the recent radio observations are Soderberg et al. (2008) for SN 2008D, Roming et al. (2009) for SN 2008ax, and Soderberg et al. (2010) for SN 2009bb; other references can be found in Chevalier & Fransson (2006). The dashed lines show the mean velocity of the radio shell if SSA is responsible for the flux peak; a particle spectral index p = 3 is assumed (see Chevalier 1998).