Kaufman, Stuart J. (2001). Modern hatreds: the symbolic politics of ethnic war. New York: Cornell University Press. стр. 193. ISBN978-0-8014-8736-1. „The key fact about Macedonian nationalism is that it is new: in the early twentieth century, Macedonian villagers defined their identity religiously—they were either "Bulgarian," "Serbian," or "Greek" depending on the affiliation of the village priest. While Bulgarian was most common affiliation then, mistreatment by occupying Bulgarian troops during WWII cured most Macedonians from their pro-Bulgarian sympathies, leaving them embracing the new Macedonian identity promoted by the Tito regime after the war.”
Conference, Foundation for Endangered Languages; Argenter, Joan A.; McKenna Brown, R. (2004). On the Margins of Nations. google.bg. Institut d'Estudis Catalans. ISBN9780953824861.
Joshua A. Fishman; Ofelia García (2010). Handbook of Language & Ethnic Identity. Oxford University Press. стр. 276. ISBN978-0-19-537492-6. „There were almost no remnants of a Bulgarian ethnic identity; the population defined itself as Christians, according to the Ottoman system of millets, that is, communities of religious beliefs. The first attempts to define a Bulgarian ethnicity started at the beginning of the 19th century.”
During the 20th century, Slavo-Macedonian national feeling has shifted. At the beginning of the 20th century, Slavic patriots in Macedonia felt a strong attachment to Macedonia as a multi-ethnic homeland. They imagined a Macedonian community uniting themselves with non-Slavic Macedonians... Most of these Macedonian Slavs also saw themselves as Bulgarians. By the middle of the 20th. century, however Macedonian patriots began to see Macedonian and Bulgarian loyalties as mutually exclusive. Regional Macedonian nationalism had become ethnic Macedonian nationalism... This transformation shows that the content of collective loyalties can shift.Roth, Klaus; Brunnbauer, Ulf (2010). Region, Regional Identity and Regionalism in Southeastern Europe, Ethnologia Balkanica Series. LIT Verlag Münster. стр. 127. ISBN978-3825813871.
"Most of the Slavophone inhabitants in all parts of divided Macedonia, perhaps a million and a half in all – had a Bulgarian national consciousness at the beginning of the Occupation; and most Bulgarians, whether they supported the Communists, VMRO, or the collaborating government, assumed that all Macedonia would fall to Bulgaria after the WWII. Tito was determined that this should not happen. "Woodhouse, Christopher Montague (2002). The struggle for Greece, 1941–1949. C. Hurst & Co. Publishers. стр. 67. ISBN978-1-85065-492-6.
"At the end of the WWI there were very few historians or ethnographers, who claimed that a separate Macedonian nation existed... Of those Slavs who had developed some sense of national identity, the majority probably considered themselves to be Bulgarians, although they were aware of differences between themselves and the inhabitants of Bulgaria... The question as of whether a Macedonian nation actually existed in the 1940s when a Communist Yugoslavia decided to recognize one is difficult to answer. Some observers argue that even at this time it was doubtful whether the Slavs from Macedonia considered themselves to be a nationality separate from the Bulgarians.Danforth, Loring M. (1997). The Macedonian conflict: ethnic nationalism in a transnational world. Princeton University Press. стр. 65—66. ISBN978-0-691-04356-2.
"A detailed analysis is made of the assimilation process which took place between Slavs and Thracians. It ended in the triumph of the Slav element and in the ultimate disappearance of the Thracian ethnos...Attention is drawn to the fact that even though assimilated, the Thracian ethnicon left behind traces of its existence (in toponymy, the lexical wealth of the Bulgarian language, religious beliefs, material culture, etc.) which should be extensively studied in all their aspects in the future..." For more see: Димитър Ангелов, Образуване на българската народност, (Издателство Наука и изкуство, “Векове”, София, (1971), pp. 409–410. ([http://macedonia.kroraina.com/da/da_summary.htm Summary in English).