TY  - RPRT
TI  - The marked item technique: a practical procedure for litter control.
AU  - S C Hayes
AU  - V S Johnson
AU  - J D Cone
PY  - 1975
DO  - 10.1901/jaba.1975.8-381
UR  - https://pubmed.ncbi.nlm.nih.gov/16795503/
ID  - 16795503
ER  -