Variability is the hallmark of aphasic behaviour: grammatical behaviour is no exception.
Kolk
Herman
H
D001037:Aphasia / Q000503:physiopathology*; D001921:Brain / Q000503:physiopathology*; D006801:Humans; D008037:Linguistics; D013067:Speech Perception / Q000502:physiology*; D014705:Verbal Behavior / Q000502:physiology*