¹⁰  The most informative and substantive introduction to Bulgarian Chant in English is the article by Elena Toncheva (1991), cited above. Unfortunately there are no other easily accessible up-to-date sources on that subject in English, while standard encyclopaedic sources are mostly silent. The Grove Dictionary provides a subchapter within Russian and Slavonic Church Music, which is focused primarily upon what is as yet unknown or uncertain about the history of Bulgarian Chant and does not contain almost any substantial information. Not only is that article now outdated, but it is also somewhat misleading with its selectivity of focus and is therefore not recommended. There are several articles of narrower scope in English by Stefan Lazarov in: Studies in Eastern Chant, (University of Oxford Press, St Vladimir’s Seminary Press) 1966-90), vol. 3 (1973), vol. 6 (1990). Available is also Raina Palikarova-Verdeil’s Doctoral dissertation in French (see bibliography), which however is from the 1950’s. The body of research that is most substantial and up to date is in Bulgarian and I will be referring many of these sources in the course of the discussion. Although that research is accessible only to researchers who use Slavic languages, some of it might hopefully be translated into English in the future.