1. Bos M.G. (Ed) (1989). Discharge measurement structures. 3 rd Revised Edition.
2. Publication 20. International Institute for Land Reclamation and Improvement
3. Used Pipe Entrances First Progress Report National Bureau of Standards NBS
4. Report Number 4444 Washington DC. Normann J. M. Houghtalen R. J. and Johnston W. J. (2001). Hydraulic Design of