Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
sach ky » sac ky, sach ty, sach kem
van hac » van hoc, van ha, van hai
hac dat » hoc dat, tac dat, hoach dat
va tinh » may tinh
tinh vi » trinh vi, tinh voi, tinh va
ma hoi » mai hoi, ma hoa, me hoi
vi cua » vai cua, di cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu ((sach ky) OR (sach y)) nang ((ma hoi) or (xa hoi)). hieu van hac dat va tinh vi cua vat~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu ((sach ky) OR (sach y)) nang ((ma hoi) OR (xa hoi)). hieu van hac dat va tinh vi cua vat.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu ((sach ky) OR (sach y)) nang ((ma hoi) or (xa hoi)). hieu van hac dat va tinh vi cua vat".
• Adding a wildcard symbol may retrieve word variants: thu ((sach ky) OR (sach y)) nang ((ma hoi) or (xa hoi)). hieu van hac dat va tinh vi cua vat*.