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 der » variation des, variation bei, variation _
de afrique » de l'afrique, en afrique, l afrique
der oral » der moral, der ort, der orte
der der » oder der, der de, der den

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

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