Perhaps you should try some spelling variations:
optical communications » optic communication, political communication, digital communications
communications costs » communication costs, communications _
parent information » patent information, payment information, patient information
techniques parent » techniques part, techniques prendre, techniques pt
2.2 developing » 3.2 developing, 3.3 developing, 2.2 development
developing 4 » developing _, developing a, developing e
aid optical » bio optical, iii optical, sfdi optical
costs 2.2 » costs 4.2, costs 2.3, cost 2.2
4 areal » 4 real, _ areal, 2 areal

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

• Adding a wildcard symbol may retrieve word variants: techniques parent information _ aid optical communications costs 2.2 developing 4 areal.*.