Molecular Line Observations of the SiO Maser Source IRAS 19312+1950
  IRAS 19312+1950 is a unique SiO maser source, exhibiting a rich set of molecular radio lines, although SiO maser sources are usually identified as oxygen-rich evolved stars, in which chemistry is relatively simple comparing with carbon-rich environments. The rich chemistry of IRAS 19312+1950 has raised a problem in circumstellar chemistry if this object is really an oxygen-rich evolved star, but its evolutional status is still controversial. In this paper, we briefly review the previous observations of IRAS 19312+1950, as well as presenting preliminary results of recent VLBI observations in maser lines. 
Jun-ichi Nakashima (1), Shuji Deguchi (2), Hiroshi Imai (3), Athol   Kemball (4) ((1) U of Hong Kong, (2) NRO, (3) Kagoshima...