Dear Flavio,
you are right that "Wings to Awakening" is a poetic translation. i was not
aware that it is the "common" translation for bodhi-pakkhiya-dhamma. If you
want as complete an introduction to the 37 factors as you can get i suggest
that you buy a copy of "The Buddhist Path to Awakening" by R M L Gethin,
published last year by Oneworld books. It is available through Amazon in
paperback. It was Dr Gethin's PhD thesis at Manchester University in England
and is comprehensive account of the textual references to the 37 factors,
covered by each factor and by group of factors. It is a wonderfully written
book and it has been very helpful to me in coming to appreciate the
interwoven complexity of the Buddha's teaching.