Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
kho tang » cao tang
vu sach » vu bach, su sach, vu khach
tinh vi » trinh vi, tinh voi, tinh va
va tinh » may tinh
cac toc » cac toi, cac nuoc, cac thoi
cac tuc » cac tu, cac tac, cac nuoc
ky tang » ky nang, ky dang, ky trong
cuu tre » cua tre, cau tren, cau treo
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) OR (kho tang)) xa hoi. hieu van ((cac tuc) or (cac toc)) va tinh vi cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach ((ky tang) OR (kho tang)) xa hoi. hieu van ((cac tuc) OR (cac toc)) va tinh vi cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu sach ((ky tang) OR (kho tang)) xa hoi. hieu van ((cac tuc) or (cac toc)) va tinh vi cuu tre".
• Adding a wildcard symbol may retrieve word variants: vu sach ((ky tang) OR (kho tang)) xa hoi. hieu van ((cac tuc) or (cac toc)) va tinh vi cuu tre*.