Important links for class4
http://www.class4exam.com/casestudy_onboard.html
http://www.class4exam.com/ic_presentation.html
http://www.class4exam.com/marineaux_presentation.html
http://www.class4exam.com/presentations.html
http://www.class4exam.com/electrical_presentation.html
http://www.class4exam.com/marineref_presentation.html
http://www.class4exam.com/presentations.html