00348nam a2200121 a 450000500170000002000140001708200160003110000230004724500470007026000390011730000210015649000490017720251203110235.0  a080393776  a300.72bDEV  aDeVillis, Robert F  aScale developmentbtheory and applications  aNew DelhibSage publicationsc1991  a121p.c22cm. PB.  aApplied social research methods seriesdv.26