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http://www.excelspeedgen.com
http://it.uom.gr/intro/cov.htm
http://genetictraining.com/onlinecourses/spsheet.htm
http://www.aewnet.com/newsgroups/
http://www.microsoftexceltraining.com/
http://businesscalculators.com/
http://www.spreadsheetworld.com/
http://www.microsoftexceltraining.com/Excel/default.htm
http://www.usd.edu/trio/tut/excel/
http://www.functionx.com/excel/
http://www.mathtools.net/Excel/
http://www.mindspring.com/~tflynn/excelvba.html
http://www.fgcu.edu/support/office2000/excel/
http://www.mrexcel.com/
http://www.j-walk.com/ss/excel/
http://www.rhodes.aegean.gr/gr/Ypiresie/shmeioseis/excel.htm