Perhaps you should try some spelling variations:
cac thuc » cach thuc, cac thu, can thuc
hieu cua » hieu qua, dieu cua, bieu cua
vai cua » dai cua, hai cua, lai cua
va danh » va dinh, va dan, dia danh
va hanh » van hanh, va thanh, ban hanh
so sach » bo sach, co sach, hoc sach
so sanh » do sanh
lang xa » lang ha, dang xay, lang van
cua tuc » cua duc, cua tu, cua thuoc
v lang » va lang, o lang, _ lang

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((so sach) or (so sanh)) v lang xa hoi. hieu cua cac thuc ((va hanh) OR (va danh)) vai cua tuc~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((so sach) OR (so sanh)) v lang xa hoi. hieu cua cac thuc ((va hanh) OR (va danh)) vai cua tuc.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((so sach) or (so sanh)) v lang xa hoi. hieu cua cac thuc ((va hanh) OR (va danh)) vai cua tuc".
• Adding a wildcard symbol may retrieve word variants: ((so sach) or (so sanh)) v lang xa hoi. hieu cua cac thuc ((va hanh) OR (va danh)) vai cua tuc*.