Perhaps you should try some spelling variations:
personal communication » interpersonal communication
developpement et » developpement des, developpement de, development east
rheologie de » rheologie des, theologie der, theologie des
de variation » der variation, die variation, does variation
2.1 personal » 3.1 personal, 2.3 personal, 2.4 personal
et afrique » en afrique, l afrique
2 set » _ set, a set
2 et » 12 et, 2 ets, 2 get

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

• The words AND, OR and NOT may confuse the search; try adding quotes: "rheologie de variation _ 2.1 personal communication ((2 et) OR (2 set)) developpement et afrique.~".
• Adding a wildcard symbol may retrieve word variants: rheologie de variation _ 2.1 personal communication ((2 et) OR (2 set)) developpement et afrique.*.