The phrase "areas of which" is correct and usable in written English.
It can be used to refer to specific areas that have been previously mentioned or are known in the context of the discussion.
Example: "The report highlighted several areas of which the committee should take note for future improvements."
Alternatives: "areas that" or "regions of which".
What about the manufacturing towns, vast areas of which are now derelict and dilapidated?
The areas of which he had oversight are part of the S.E.C.'s inquiry.
And, along with changing ethnic and racial attitudes, affirmative action has helped promote a powerful global popular culture, many areas of which are dominated by minorities.
The new restrictions apply to the county's unincorporated areas, of which East Los Angeles, which lies just east of downtown, is the most populated.
These 14 hotspots can be grouped into eight geographic areas, of which five largely are unprotected at this time.
At present we have tested 23 brain areas of which four have given definite positive responses (ie inactivity) and two potentially positive responses.
New environmental laws are aimed at protecting Brazil's Amazon rain forest, large areas of which are being burned by squatter farmers and speculators.
The Cornell Graduate School is organized into more than ninety major fields of study, or subject areas, of which public affairs is one.
Caribou, musk oxen, foxes, and bears inhabit the Barren Grounds, large areas of which are protected by the Queen Maud Gulf Migratory Bird Sanctuary and Thelon Wildlife Sanctuary.
The process has been especially controversial in New York, areas of which lie atop a large shale formation, mostly because of concern over its environmental impact.
An overhead view adds to the North's current intelligence, particularly in high-security areas, of which human sources on the ground may have only limited knowledge.
