TY  - RPRT
TI  - Report of the U.S. Geological Survey's evaluation program for standard reference samples distributed in April 1993; T-123 (trace constituents), T-125 (trace constituents), M-126 (major constituents, N-38 (nutrients), N-39 (nutrients), P-20 (low ionic strength, and Hg-16 (mercury)
AU  - H.K. Long
AU  - J.W. Farrar
PY  - 1993
DO  - 10.3133/ofr93436
UR  - https://pubs.usgs.gov/publication/ofr93436
ID  - ofr93436
ER  -