7Foley, William & Mike Olson 1985 Clausehood and verb serialization. In Johanna Nichols and Anthony Woodbury, ed. Grammar Inside and Outside the Clause .17- 60. Combridge University Press.
8Foley, William A. and Van Valin, Robert D., Jr. 1984 Functional Syntax and Universal Grammar. Cambridge: Cambridge University Press.
9Haboud, Marleen 1997 Grammaticalization, clause union and grammatical relations in Ecuadorian Highland Spanish, in Givón ed. Grammatical Relations: a Functionalist Perspective: 199- 227. Amsterdam; Philadelphia: J. Benjamins.
10Hopper, Paul J. and Elizabeth Closs Traugott 1993 Crammaticalization, Cambridge University Press.
