I am wondering whether it is OK to use a noun to modify a couple of other nouns. For example, is it correct to write:
The computer brands HP, DELL, Apple and IBM are becoming the symbols of IT industry.
The cities New York, Chicago, Philadelphia, and Boston are where I want to go.
I know it is usually considered acceptable in oral English, but I am wondering if it is OK for them to this usage to appear in formal writings?