Withrow, J. (1987). Effective writing: Writing skills for intermediate students of american english Teacher´s Manual and answer Key. Cambridge University Press.

Withrow, Jean. Effective Writing: Writing Skills for Intermediate Students of American English Teacher´s Manual and Answer Key. Cambridge: Cambridge University Press, 1987.

Withrow, Jean. Effective Writing: Writing Skills for Intermediate Students of American English Teacher´s Manual and Answer Key. Cambridge University Press, 1987.