This question has been re-posted in General Real Estate Investing. Thanks.
Try your county's tax database at www.netronline.com
It may have a special code for commercial buildings. Here '4c' properties are apartment buildings, '4b' - store fronts and '4a' - mixed use. Yours may have something similiar which may allow you to look up all properties with a 'commercial' designation. Good luck.
Loopnet has a list of commercial properties. Once you get the address, find your local county GIS and find the owner of the property. Most counties have a local GIS online where you can parsel search or search by address.
do you have link?
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