Perhaps you should try some spelling variations:
variation models » valuation models, evaluation models, variation des
communication 3 » communication _, communication a
ideologie der » ideologie und, typologie der
der variation » de variation, does variation, die variation
case project » based project
models case » model case, models based
3 gas » _ gas, 2 gas

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

• Adding a wildcard symbol may retrieve word variants: ideologie der variation models case project communication 3 gas development 1 africa.*.