Perhaps you should try some spelling variations:
hoc sach » hoc cac, hoc anh
hanh tai » thanh tai, hang tai, han tai
hieu van » hieu va, thien van, lieu va
dang vat » dang van, dong vat, dang nhat
dang va » dang van, hang va, dung va
nam tuc » nam thuc, nam truc, nam tu
va hanh » van hanh, va thanh, va danh
tuc va » thuc va, truc va, tuc xa
cuc tu » cuc du, luc tu, duc tu

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) OR (hoc sinh)) y ((dang va) or (dang vat)) hoi. hieu van nam tuc va hanh tai cuc tu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((hoc sach) OR (hoc sinh)) y ((dang va) OR (dang vat)) hoi. hieu van nam tuc va hanh tai cuc tu.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((hoc sach) OR (hoc sinh)) y ((dang va) or (dang vat)) hoi. hieu van nam tuc va hanh tai cuc tu".
• Adding a wildcard symbol may retrieve word variants: ((hoc sach) OR (hoc sinh)) y ((dang va) or (dang vat)) hoi. hieu van nam tuc va hanh tai cuc tu*.