Mark K. is surely right about St Nedelia. This word means literally "no business" or "no transactions," that is, "no work", and referred to Sunday. It still has that meaning in most Slavic languages. Russian, however, adopted _Voskresenie_ 'Resurrection' as the word for Sunday, and then gave _nedelia_ the meaning of 'week'. I don't know when this occurred, but it must have been pretty early, because 'week' in Latvian is also nedelia (sorry I can't put in the proper diacriticals; the second _e_ is long, the _l_ is soft); clearly borrowed from Russian, and I think it must have happened before the 13th century.

St Petka is to be identified in the same way. She is St Pareskeva; this is Greek for 'Preparation', and in the Hellenistic period meant in Jewish usage 'Friday', the day of preparation for the Sabbath. In Russian Slavonic, she is called _Piatnitsa_ 'Friday', obviously from the word for 'five' (for some reason, while Greeks count Sunday as the first day of the week, Slavs reckon Monday as the first, a convention that also is reflected in Latvian). _Petka_ comes from the same root, the old letter being pronounced _ia_ in some languages and _e_ in others. It is, however, a popular form with the diminutive _-ka_.

So these are in fact not just local Bulgarian saints but are in the Greek Menaion; only they are a bit disguised by the translation of their names. They are not the only ones; St Photini becomes Svetlana in Slavic, Lumenita in Romanian.

Stephen R.