sentences:  Instead of relying solely upon intra-linguistic evidence and data to explain language change, socio-historical linguists search for extra-linguistic causes of change.One of the seminal works in the field is Romaine (1982)'s "Socio-Historical Linguistics".Other studies such as John McWhorter's work, "The Missing Spanish Creoles", are more specific in this case examining the extra-linguistic reasons why there are no creoles with Spanish as a lexifier language (as opposed to English, French, Dutch, Portuguese, etc.