TY  - RPRT
TI  - Directional selectivity and its use in early visual processing.
AU  - D Marr
AU  - S Ullman
PY  - 1981
DO  - 10.1098/rspb.1981.0001
UR  - https://pubmed.ncbi.nlm.nih.gov/6111795/
ID  - 6111795
ER  -