Regarding the greek spelling read the articles of Babiniotis in
http://www.babiniotis.gr/wmt/webpages/index.php?lid=1&pid=16&catid=4&apprec=13
and
http://www.tanea.gr/politismos/article/?aid=58040
Regarding the basic rules of the greek spelling consult the following website
http://www.e-keimena.gr/index.php?option=com_content&view=article&id=75:2009-10-17-18-10-22&catid=91:2009-10-17-17-53-41&Itemid=53