1922_Ferdinand Schevill – ‘The History of the Balkan Peninsula’, Pg. 422.

Вероучение - Поука 03

These Slavs may properly be considered as a special
Macedonian group, but since they were closely related to both
Bulgars and Serbs and had, moreover, in the past been usually
incorporated in either the Bulgar or Serb state, they inevitably
became the object of both Bulgar and Serb aspirations and an
apple of bitter discord between these rival nationalities. As an
oppressed people on an exceedingly primitive level, the
Macedonians Slavs had as late as the congress of Berlin exhibited
no perceptible national consciousness of their own…in fact, so
indeterminate was the situation that under favorable
circumstances they might even develop their own Macedonian
consciousness.