Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
cau tren » cu tren, dau tren, ca tren
hoc cac » hoc cao
tang ma » mang may, tang van
van cau » van dau, van hau, van chat
cau duc » cao duc, cau luc, chu duc
va dinh » van dinh, va kinh, va tinh
dinh vi » dinh ve, dinh viet, dinh tri
vi cau » va cau, ve cau, di cau

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc cac ky ((nang cao) or (tang ma)) hoi. hieu van cau duc va dinh vi cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc cac ky ((nang cao) OR (tang ma)) hoi. hieu van cau duc va dinh vi cau tren.
• Adding a wildcard symbol may retrieve word variants: hoc cac ky ((nang cao) or (tang ma)) hoi. hieu van cau duc va dinh vi cau tren*.