Perhaps you should try some spelling variations:
dinh viet » ninh viet, trinh viet, sinh vien
danh viet » anh viet, ninh viet, nang viet
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, lieu va
hieu ve » hieu va
sach ty » sach y, sach tu, sach thu
cac duc » cac du, cao duc, cac dac
nang ma » tang ma, sang ma, nang cao
ty nang » ky nang, ty xang, ty hang
cua tre » cua te, cuu tre, cua triet
ma hoi » mai hoi, xa hoi, ma hoa

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach ty nang ma hoi. ((hieu ve) OR (hieu van)) cac duc va ((dinh viet) or (danh viet)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ty nang ma hoi. ((hieu ve) OR (hieu van)) cac duc va ((dinh viet) OR (danh viet)) cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ty nang ma hoi. ((hieu ve) OR (hieu van)) cac duc va ((dinh viet) or (danh viet)) cua tre*".