text: Some Kajkavian words bear a closer resemblance to other Slavic languages such as Russian than they do to Shtokavian or Chakavian. For instance gda (also seen as shorter "da") seems to be at first glance unrelated to kada, however when compared to Russian когда, Slovene kdaj, or Prekmurje Slovene gda, kda, the relationship becomes apparent. Kajkavian kak (how) and tak (so) are exactly like their Russian cognates and Prekmurje Slovene compared to Shtokavian, Chakavian, and standard Slovene kako and tako. (This vowel loss occurred in most other Slavic languages; Shtokavian is a notable exception, whereas the same feature in Macedonian is probably not due to Serbo-Croatian influence because the word is preserved in the same form in Bulgarian, to which Macedonian is much more closely related than to Serbo-Croatian).
  History of research
  Linguistic investigation began during the 19th century, although the research itself often ended in non-linguistic or outdated conclusions. Since that was the age of national revivals across Europe as well as the South Slavic lands, the research was steered by national narratives. Within that framework, Slovene philologists such as Franz Miklosich and Jernej Kopitar attempted to reinforce the idea of Slovene and Kajkavian unity and asserted that Kajkavian speakers are Slovenes. On the other hand, Josef Dobrovský also claimed linguistic and national unity between the two groups but under the Croatian ethnonym.