Other
How Herbicides Work
A basic explanation of the different types of herbicides and how they work is covered in this resource. This is followed by a more technical discussion of the classes of herbicides.
Davidson College
Herbicides: Background
A concise site that provides interesting facts, history, and methods of classifying herbicides.
Other
How Do Herbicides Work?
What is a herbicide? How do herbicides work? What are the target sites for herbicides? Why do herbicides kill plants? What are some selective and non-selective types of herbicides? These questions are answered in this informative site.
NC State University
Postemergence Herbicides
This competent site lists a number of postemergence selective and non-selective herbicides, their characteristics, and uses.