Pre-main sequence candidates in the very young open cluster NGC 6611D. de Winter, C. Koulis, P. S. Thé, M. E. van den Ancker, M. R. Pérez and E. A. BiboAstron. Astrophys. Suppl. Ser., 121 2 (1997) 223-242DOI: https://doi.org/10.1051/aas:1997284