Student in need of some guidance on zoning, use and parking

[Nicholas Williams]

I am a student in the undergraduate real estate program at the University of North Texas working a project to increase the profitability of a medical office building in Dallas, Tx.  We are having some trouble confirming the building is zoned as "General Office" and the requirements for available parking. The property currently has a 3:1,000 sqft parking ratio which in practice only allows half of the building to be leased. 

What are some good places to find zoning use and parking requirements?