Perhaps you should try some spelling variations:
thanh tai » thanh hai, thanh toan, thanh san
hoc sach » hoc sinh, hoc cac, hoc anh
hieu cua » hieu qua, dieu cua, bieu cua
sach ty » sach y, sach tu, sach thu
ca viet » va viet, co viet, hoa viet
lo van » le van, vo van, so van
ang xa » lang xa, mang xa, dang xay
ty ang » ty xang, ty hang, ty anh
lo va » lao va, ly va, le va

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc sach ty ang xa hoi. hieu cua cac ((lo va) or (lo van)) ((thanh tai) OR (doanh tai)) ca viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc sach ty ang xa hoi. hieu cua cac ((lo va) OR (lo van)) ((thanh tai) OR (doanh tai)) ca viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc sach ty ang xa hoi. hieu cua cac ((lo va) or (lo van)) ((thanh tai) OR (doanh tai)) ca viet".
• Adding a wildcard symbol may retrieve word variants: hoc sach ty ang xa hoi. hieu cua cac ((lo va) or (lo van)) ((thanh tai) OR (doanh tai)) ca viet*.