TY  - RPRT
TI  - Why did they quit?
AU  - L. E. Holland Bartels
AU  - R.C. Hubley
PY  - 1988
DO  - 10.1577/1548-8446-13-2
UR  - https://pubs.usgs.gov/publication/1003444
ID  - 1003444
ER  -