Dear Kiriaki,
Nikola Popomihajlov published this (theory & practice) book in october this year, so, at this moment, it`s not available online.
My modest reflection is very positive - author made concept very receptive for everyone. Also, it seems that the basic intention of author is liturgical participation of his students; almost all exercise examples are taken from sunday and holiday Liturgy.
I have chanting lessons every saturday and I will ask it`s author to share with us his opinion about this uncommon ecclesiastical and cultural happening.