Model codes, often proposed by an organization that has studies the land use issues at hand, can be a great jumping off point for your research. They will often be accompanied by some commentary that describes the development of the code, and may list municipalities that are known to have adopted the language in the model code.
In addition to these collections of model codes, model codes can be found on various websites, drafted by a variety of groups, relating to specific aspects of land use law.
The American Planning Association provides the text of several enabling acts and related materials.
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