Perhaps you should try some spelling variations:
developed countries » developing countries
state development » estate development, stable development, staff development
development under » development index, development united, development center
model developed » code developed, mode developer, model development
under programm » lander programm, und programm, der programm
1e model » fe model, 5e model, cge model

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (( _ state development under programm. ) or ( 1e model developed countries problems. ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( _ state development under programm. ) OR ( 1e model developed countries problems. )).
• Adding a wildcard symbol may retrieve word variants: (( _ state development under programm. ) or ( 1e model developed countries problems. ))*.