Παραπομπή APA

Williams, H. M. (1991). An essential english grammar with usage and composition. Calicut University.

Παραπομπή Chicago Style

Williams, H. M. An Essential English Grammar with Usage and Composition. Kozhikode: Calicut University, 1991.

Παραπομπή MLA

Williams, H. M. An Essential English Grammar with Usage and Composition. Calicut University, 1991.