Hugo' s Simplified System. (1969). Italian in three months. Hugo's Language Books.
Citazione stile Chigago Style (17a edizione)Hugo' s Simplified System. Italian in Three Months. Londres: Hugo's Language Books, 1969.
Citatione MLA (9a ed.)Hugo' s Simplified System. Italian in Three Months. Hugo's Language Books, 1969.
Attenzione: Queste citazioni potrebbero non essere precise al 100%.