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Published online by Cambridge University Press: 12 April 2016
The results of the He, N and C abundance determinations for MS early B-stars, summarized in the review [1], lead to the inference that there are evolutionary variations in atmospheric contents of these elements. The conclusion was made that CNO-cycle products emerge on a surface of B-stars during their MS phase yet and such appearance can be considered as a probable manifestation of some mixing process between outer layers and stellar interiors. In particular the N enrichment with the age was found, which reachs about 1.0 dex for most massive B-stars (see [1,2]). However Gies and Lambert [3] (further GL) investigated recently the C, N and O abundances in a sample of early B-stars and did not confirm such great N enrichment. Since the problem of early mixing is very important for the understanding of first evolutionary stages of massive stars, the GL data need further and thorough analysis.