Hengeveld, Kees. 1989. Layers and Operators in Functional Grammar. Journal of Linguistics 25. 127-157.
@article{Hengeveld-1989, author = {Hengeveld, Kees}, journal = {Journal of Linguistics}, pages = {127-157}, title = {Layers and Operators in Functional Grammar}, volume = {25}, year = {1989} }