Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac, hoc anh
can thuc » dan thuc, cay thuc, san thuc
van thuc » va thuc, dan thuc, van thu
va triet » va thiet, va trien, ve triet
co sach » bo sach, cuon sach
lang xa » lang ha, dang xay, lang van
va lang » va nang, hoa lang
lang di » lang dai, hang di, lang du
y lang » o lang, _ lang, tay lang
di va » dai va, di vao, doi va

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((co sach) OR (hoc sach)) y lang xa hoi. hieu qua ((can thuc) or (van thuc)) va lang di va triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((co sach) OR (hoc sach)) y lang xa hoi. hieu qua ((can thuc) OR (van thuc)) va lang di va triet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((co sach) OR (hoc sach)) y lang xa hoi. hieu qua ((can thuc) or (van thuc)) va lang di va triet*".