Perhaps you should try some spelling variations:
oral communication » personal communication
ontologies based » ontology based, colonies based, ontologies a
de developpement » sme development
developpement de » developpement des, developpement durable
based variation » based validation, based valuation, based vaccination
variation oder » variation der, variation over, variation des
de afrique » de l'afrique, en afrique, l afrique
oder den » oder der, wider den, uber den
den oral » den ort, new oral
a de » a die, a der, a des

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

• Adding a wildcard symbol may retrieve word variants: ontologies based variation oder den oral communication a de developpement de afrique.*.