Mr. Younes - Thank you for the kind comments. Here are some links to some of the books I've written on this subject ... www.turvac.com/HTMLs/ProductHTMLs/shalhandbook.html www.turvac.com/HTMLs/ProductHTMLs/bsshalwrkbk_english_printed.html www.turvac.com/HTMLs/ProductHTMLs/bsshalwrkbk_english_ebook.html www.turvac.com/HTMLs/ProductHTMLs/shalssg_english.html Than you for your interest! John Piotrowski