TY  - RPRT
TI  - Surface structure, deep structure, and transformations: a model for syntactic development.
AU  - W A Hass
AU  - J M Wepman
PY  - 1969
DO  - 10.1044/jshd.3404.303
UR  - https://pubmed.ncbi.nlm.nih.gov/5349138/
ID  - 5349138
ER  -