http://www.go-online.gr/ebusiness/specials/article.html?article_id=1446
http://library.panteion.gr:8080/dspace/bitstream/123456789/964/1/spyrou.pdf
http://library.panteion.gr:8080/dspace/bitstream/123456789/794/1/dimoulas.pdf
http://www.econ.uoi.gr/seminars_oikonimia_koinonia/dialeksi3/pdf.pdf
http://library.panteion.gr:8080/dspace/bitstream/123456789/964/1/spyrou.pdf
http://library.panteion.gr:8080/dspace/bitstream/123456789/794/1/dimoulas.pdf
http://www.econ.uoi.gr/seminars_oikonimia_koinonia/dialeksi3/pdf.pdf