Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
cac thoi » cac toi, cac hop, cac tro
vu sach » vu bach, su sach, vu khach
cac toc » cac toi, cac nuoc
tinh vi » trinh vi, tinh voi, tinh va
cuu tre » cua tre, cau tren, cau treo
sach ky » sac ky, sach y, sach ty
cac tuc » cac tu, cac tac, cac nuoc
tang xa » trang xa, tang ma, lang xa
ky tang » ky nang, ky dang, kho tang
vi cuu » vi luu, vinh cuu

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu sach ky tang xa hoi. hieu van ((cac tuc) or (((cac toc) OR (cac thoi)))) may tinh vi cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach ky tang xa hoi. hieu van ((cac tuc) OR (((cac toc) OR (cac thoi)))) may tinh vi cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu sach ky tang xa hoi. hieu van ((cac tuc) or (((cac toc) OR (cac thoi)))) may tinh vi cuu tre".
• Adding a wildcard symbol may retrieve word variants: vu sach ky tang xa hoi. hieu van ((cac tuc) or (((cac toc) OR (cac thoi)))) may tinh vi cuu tre*.