Stellar complexes in M33
  A method for identification of stellar complexes in M33 is applied. Several OB associations form a stellar complex with mean size of 0.3 - 1 kpc. We apply a correlation technique to compare different stellar populations in M33. Our results confirm the existence of a strong correlation between OB stars, HII regions and WR stars, which trace the regions of massive star formation. There is a good correlation between red supergiants (RSGs) and WR stars in the spiral arms of M33. This can be expected since the progenitors of WR stars are massive OB stars or RSGs with masses greater than 20 M_sun. The massive RSGs and WR stars probably originate from nearby sites of star formation. We consider this fact as a ground for identification of stellar complexes in M33. The presented method for identification of stellar complexes can be applied to other nearby galaxies. 
G. R. Ivanov