Two generations in stellar complexes and associations in M 33 galaxy and   their spatial correlation
  Massive stellar content of stellar complexes and associations in M 33 is studied combining deep UBV photometry from the Local Group Survey (Massey et al. 2006) and JHK photometry from the 2MASS. Two basic populations (incl. OB stars and red supergiants) are distinguished and their application for reconstruction of the star formation process in this galaxy are discussed. 
Todor Veltchev, Nina Koleva, Petko Nedialkov, G. R. Ivanov
astro-ph.GA