Website 1: http://antoine.frostburg.edu/chem/senese/101/moles/faq/why-use-moles.shtml
Website 2: http://chemistry.about.com/od/workedchemistryproblems/a/molegramconvert.htm
Website 3: http://www.softschools.com/quizzes/chemistry/counting_particles_and_avogadros_number/quiz1119.html