SIMBAD references

begin{tex}We have measured M67 stars in a Strömgren-βsystem based ultimately on data for the Hyades and Coma clusters. By comparing our results to previously published data, we have derived formal corrections required to put the other data on our system. Corrections which are statistically significant by our criteria are found for Strömgren measurements made by Strom et al. (1971, PASP, 83, 768). Those corrections range between 36 and 61 mmag. In addition, corrections of 17 and 8 mmag, respectively, are found for βmeasurements made by Eggen (1981, ApJ, 247, 503) and Nissen et al. (1987, AJ, 93, 634). In addition to considering M67, we have updated earlier work of ours which was done on Praesepe and NGC 752. After revising our criterion for statistical significance, we have changed our judgment about two corrections which we had derived for published data for those clusters. Further work will be required to verify the reality of those corrections. We have also compared our results to closely similar work which was done by Nissen (1988, A&A, 199, 146) and which had previously escaped our notice. Differences between our results and those of Nissen appear to exist for βin Praesepe and for c_1 in NGC 752. Independent measurements support our Praesepe result, but the problem for NGC 752 remains unresolved.