TY - JOUR
AU - 
JF - Problems and Methods in Longitudinal Research
DO - 10.1017/cbo9780511663260.003
DA - 1991-12-12
UR - https://www.deepdyve.com/lp/crossref/HpufCuJ9tB
SP - 1
EP - 27
DP - DeepDyve
ER -