SIMBAD references

The light-change of the Mira stars RT Boo, TV Peg and VX Aur was analyzed on three ways for a long time. In the first period I estimated the brightness of the variables on sky monitoring photo plates (red spectral range) from Sonneberg Observatory with Argelander's Method, in the last years I measured scanned photo plates with a photometry program and in addition I used visual observations from A.A.V.S.O. for the analysis. The behavior of the periods of the tree stars from 1965 to 2013 is described here.