This is an excellent presentation of Linear Programming, in the form of structured questions and answers, prepared and maintained by Prof. R. Fourer of Northwestern University, in collaboration with Argonne National Laboratories.
A book about covers a wide range of subjects concerning optimization and is a valuable source for those who want to learn more about the mathematical formulation of this type of problems. It is written by Robert J. Vanderbei from the Department of Operations Research and Financial Engineering of Princeton University and is used a course book from many Universities.
The simplex method was the first method developed to solve linear programs. In these pages, this site attempts to teach how the simplex method works. Users can select the size of the problem that they want to solve, enter the data, and watch the simplex method go through each step, of every iteration, of the method. This is a brief review on Simplex Method that mainly includes the history and the mathematical basis for this method.
Tutorials on the Simplex Method
Stefan Waner and Steven R. Costenoble from the Department of Mathematics in Hofstra University, provide us with easy tutorials and an quick quiz in linear programming.