Potto Project - Open Engineering Textbooks
URL = http://www.potto.org/
"The Potto Project was established by Dr. Genick Bar-Meir to produce and distribute high quality open textbooks. Books are made available in pdf, LaTeX (source), dvi and postscript under the GFDL. So far the main books are ‘Fundamentals of Compressible Flow’ ``Basics of Fluid Mechanics,' and ‘Fundamentals of Die Casting Design’, all the books available from the downloads page." Potto Project provides also high quality engineering education software potto-GDC - gas dynamics calculator and the largest compressible tables.