1. L. Andrejčin, K. Popov, S. Stojanov, Gramatika na bălgarskija ezik, Sofija 1977.
2. J.L. Austin, How to Do Things with Words, in J.O. Urmson (ed.), The Williams James Lectures of Harward University 1955, London 1962.
3. J.L. Austin, How to Do Things with Words, in: J.O. Urmson (ed.), The Williams James Lectures of Harward University 1955, London 1962.
4. W.F. Bakker, The Aspect of the Imperative in Modern Greek, “Neophilologus”, 1965, 2-3(49), с. 89-103, 203-210.
5. W.F. Bakker, The Aspect of the Imperative in Modern Greek, “Neophilologus”,1965, 49/2-3, с. 89-103, 203-210.