Example of how to use RDFa markup to polish your products in Google Rich Snippets. Developed by Professor Hepp, the inventor of the GoodRelations standard for e-commerce.
F. Mitzlaff, M. Atzmueller, G. Stumme, und A. Hotho. Complex Networks IV, Volume 476 von Studies in Computational Intelligence, Springer Verlag, Heidelberg, Germany, (2013)