TY  - RPRT
TI  - Direct-current arc and alternating-current spark emission spectrographic field methods for the semiquantitative analysis of geologic materials
AU  - D. J. Grimes
AU  - A. P. Marranzino
PY  - 1968
DO  - 10.3133/cir591
UR  - https://pubs.usgs.gov/publication/cir591
ID  - cir591
ER  -