Perhaps you should try some spelling variations:
cam truong » cac truong, lam truong, cao truong
cam trung » nam trung, cac trung, cao trung
van thiet » va thiet, dan thiet, can thiet
so sach » so sanh, bo sach, co sach
lang xa » lang ha, dang xay, lang van
va hanh » van hanh, va thanh, va danh
y lang » o lang, _ lang, tay lang

You may be able to get more results by adjusting your search query.

• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach y lang xa hoi. hieu qua ((cam trung) OR (cam truong)) va hanh vi van thiet~".
• Adding a wildcard symbol may retrieve word variants: so sach y lang xa hoi. hieu qua ((cam trung) OR (cam truong)) va hanh vi van thiet*.