TY  - BOOK
AU  - Diederich P B
AU  - Palmer O E
TI  - Difficulty in grades 11 and 13 of 4,800 words, from 6,000 through 20,000 in frequency
U1  - 371.26 
PY  - 1956///
CY  - New Jersey
PB  - ETS
KW  - Educational tests and measurements
ER  -