Kajkavian
The major cities in northern Croatia are located in what was historically a Kajkavian-speaking area, mainly Zagreb, Koprivnica, Krapina, Križevci, Varaždin, Čakovec. The typical archaic Kajkavian is today spoken mainly in Hrvatsko Zagorje hills and Međimurje plain, and in adjacent areas of northwestern Croatia where immigrants and the Štokavian standard had much less influence. The most peculiar Kajkavian dialect "(Baegnunski)" is spoken in Bednja in northernmost Croatia. Many of northern Croatian urban areas today are partly Štokavianized due to the influence of the standard language and immigration of Štokavian speakers.
Serbo-Croatian
Enisa Kafadar argues that there is only one Serbo-Croatian language with several varieties. This has made it possible to include all four varieties in a new grammar book. Daniel Bunčić concludes that it is a pluricentric language, with four standard variants spoken in Serbia, Croatia, Montenegro and Bosnia and Herzegovina. The mutual intelligibility between their speakers "exceeds that between the standard variants of English, French, German, or Spanish". Other linguists have argued that the differences between the variants of Serbo-Croatian are less significant than those between the variants of English, German, Dutch, and Hindi–Urdu.