optional tagmeme

Sources

• LONGACRE 1983 276

  LONGACRE, Robert E. (1983) The Grammar of Discourse. New York: Plenum Press.

• PIKE & PIKE 1982 118

  PIKE, Kenneth L. & PIKE, Evelyn G. (1982) Grammatical Analysis. Dallas: SIL & UTA.

• MATTHEWS 1997 372

  MATTHEWS, P.H. (1997) The Concise Oxford Dictionary of Linguistics. Oxford: Oxford University Press.