glaubt er, glaub ich, glaub. Integrierte V1-Parenthesen, Extraktion aus V2-Komplementen, Grammatikalisierung 

This paper investigates the function and underlying structure of integrated verb first parentheticals like glaubt sie. Written data show first and third person parentheticals with glauben to differ with regard to their preferred syntactic positions. Considering the modal particle glaub, this difference can be attributed to a greater degree of grammaticalization in the first person parentheticals. The data further suggest synchronic variation in that certain constructions can be analyzed as either main clauses containing a parenthetical in prefinite position or being instances of extraction from verb second complements. In their function as epistemic or evidential adverbials, genuine verb first parentheticals are argued not to contain traces of internal arguments or any other empty elements.