Perhaps you should try some spelling variations:
thanh van » thanh san, thanh toan, thanh phan
thanh vai » thanh hai, thanh tai, thanh oai
hieu van » thien van, lieu va, hieu ve
su sach » so sach, vu sach
nam qua » nam quan, nam cua, nam mua
qua ban » cua ban, qua quan
sach ky » sac ky, sach y, sach ty
hieu va » lieu va, hieu qua
cao hoi » cau hoi, co hoi, cao hoc
cua tre » cua te, cuu tre, cua triet

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ky nang cao hoi. ((hieu van) or (hieu va)) nam qua ban ((thanh vai) OR (thanh van)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky nang cao hoi. ((hieu van) OR (hieu va)) nam qua ban ((thanh vai) OR (thanh van)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky nang cao hoi. ((hieu van) or (hieu va)) nam qua ban ((thanh vai) OR (thanh van)) cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ky nang cao hoi. ((hieu van) or (hieu va)) nam qua ban ((thanh vai) OR (thanh van)) cua tre*.