TY  - RPRT
TI  - An optical method for determining particle sizes of coarse sediment
AU  - J.R. Ritter
AU  - E. J. Helley
PY  - 1968
DO  - 10.3133/ofr68230
UR  - https://pubs.usgs.gov/publication/ofr68230
ID  - ofr68230
ER  -