Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
vu sach » vu bach, su sach, vu khach
sach ky » sac ky, sach y, sach ty
tinh vi » trinh vi, tinh voi, tinh va
cuu tre » cua tre, cau tren, cau treo
co hoi » co hoc, co loi
xuc va » tuc va, luc va, xac va
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 nang ((co hoi) or (xa hoi)). hieu van nam ((xuc va) OR (duc va)) tinh vi cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach ky nang ((co hoi) OR (xa hoi)). hieu van nam ((xuc va) OR (duc va)) tinh vi cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu sach ky nang ((co hoi) or (xa hoi)). hieu van nam ((xuc va) OR (duc va)) tinh vi cuu tre".
• Adding a wildcard symbol may retrieve word variants: vu sach ky nang ((co hoi) or (xa hoi)). hieu van nam ((xuc va) OR (duc va)) tinh vi cuu tre*.