TY  - RPRT
TI  - Guidelines for sample collecting and analytical methods used in the U.S. Geological Survey for determining chemical composition of coal
AU  - Vernon Emanuel Swanson
AU  - Claude Huffman
PY  - 1976
DO  - 10.3133/cir735
UR  - https://pubs.usgs.gov/publication/cir735
ID  - cir735
ER  -