SIMBAD references

Small-amplitude red variables (SARVs) are M giants or supergiants which are pulsating with small amplitudes (up to 2.5 mag) and with time scales of 20 to 200 days or more. This paper reports on a ten-year study of about two dozen SARVs, carried out through the American Association of Variable Star Observers (AAVSO) photoelectric photometry program. It has provided detailed information on the regularity, period and amplitude of these stars. Most have well-defined periods in the 20 to 200 day range. Several also have a long secondary period. One (W Boo) appears to have two periods with a ratio of 2.3.