Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
hanh lai » hanh lam, hanh tai, thanh lap
sach ty » sach y, sach tu, sach thu
cao hoc » co hoc, cho hoc, chat hoc
van cam » van nam, van lam, van cau
lai cua » dai cua, hai cua, lai chau
sai ky » sac ky
tuc va » thuc va, truc va, duc va

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 ty) or (sai ky)) nang cao hoc. hieu van cam ((tuc va) or (tuc xa)) hanh lai cua vat~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so ((sach ty) OR (sai ky)) nang cao hoc. hieu van cam ((tuc va) OR (tuc xa)) hanh lai cua vat.
• Adding a wildcard symbol may retrieve word variants: so ((sach ty) or (sai ky)) nang cao hoc. hieu van cam ((tuc va) or (tuc xa)) hanh lai cua vat*.