TY  - RPRT
TI  - DIFFICULTY FACTORS AND NON-LINEAR FACTOR ANALYSIS.
AU  - R P MCDONALD
PY  - 1965
DO  - 10.1111/j.2044-8317.1965.tb00690.x
UR  - https://pubmed.ncbi.nlm.nih.gov/14324840/
ID  - 14324840
ER  -