1. Aguirre‐Pe J. (1984). “Friction and critical conditions for gravel.” Report Hydraulic Laboratory of the Universidad de Los Andes Mérida Venezuela (in Spanish).
2. Ashida K. and Bayazit M. (1973). “Initiation of motion and roughness of flows in steep channels.” Proc. 15th Congress of the Int. Assoc. for Hydr. Res. Istambul Turkey 1 475 484.