Perhaps you should try some spelling variations:
trong van » trong cac
tang van » dang van, hoang van, tang luan
so sanh » do sanh
sanh tu » anh tu, danh tu, hanh tu
hieu ve » hieu va, hieu van
truc va » thuc va, thuc vat, trung va
va hanh » van hanh, va thanh, va danh
ve cau » ke cau, va cau, ve cac
vi cua » vai cua
di cua » dai cua, doi cua, de cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sanh tu ((tang van) OR (trong van)) hoa. hieu ve cau truc va hanh ((vi cua) or (di cua)) viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sanh tu ((tang van) OR (trong van)) hoa. hieu ve cau truc va hanh ((vi cua) OR (di cua)) viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sanh tu ((tang van) OR (trong van)) hoa. hieu ve cau truc va hanh ((vi cua) or (di cua)) viet".
• Adding a wildcard symbol may retrieve word variants: so sanh tu ((tang van) OR (trong van)) hoa. hieu ve cau truc va hanh ((vi cua) or (di cua)) viet*.