Perhaps you should try some spelling variations:
optical communication » optical communications, optic communication, political communication
information gaps » information gap
communication 3 » communication _, communication a
3.1 development » 2 development
do optical » bio optical, loc optical, _ optical
gaps do » games do, gaps how, gaps vom
3 3.1 » _ 3.1, i 3.1, a 3.1

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

• Adding a wildcard symbol may retrieve word variants: technologies _ information gaps do optical communication 3 3.1 development 1 africa.*.