Bogdan, R. AND Taylor, S. (1975), Introduction to Qualitative Research Methods' , Wiley.
2.
Easterby-Smith, M. (1985), 'Management research: paradigms, purposes and issues', in A. Chapman (ed.), What Has Management Research Got to Do with Managers?, London: Association of Teachers of Management.
3.
Hamblin, A. (1974), Evaluation and Control of Training, McGraw-Hill.
4.
Hesseling, P. (1966), Strategy of Evaluation Research in the Field of Supervisory and Management Training, Assen: Van Gorcum.