Perhaps you should try some spelling variations:
thanh hai » thanh phan, thanh hoa
hieu van » hieu va, thien van, lieu va
vu sach » vu bach, su sach, vu khach
sach ky » sac ky, sach y, sach ty
van cam » van nam, van lam, van cau
cam tac » cac tac, cam tay, can tac
cua tu » cua tuc, cua su, cua cu
o hoc » mo hoc, so hoc, y hoc
gia » giao

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 ((o hoc) OR (co hoc)). hieu van cam tac gia ((thanh hai) or (thanh san)) cua tu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach ky nang ((o hoc) OR (co hoc)). hieu van cam tac gia ((thanh hai) OR (thanh san)) cua tu.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu sach ky nang ((o hoc) OR (co hoc)). hieu van cam tac gia ((thanh hai) or (thanh san)) cua tu".
• Adding a wildcard symbol may retrieve word variants: vu sach ky nang ((o hoc) OR (co hoc)). hieu van cam tac gia ((thanh hai) or (thanh san)) cua tu*.