Perhaps you should try some spelling variations:
hanh gian » thanh gian, thanh giang, manh giang
hieu van » hieu va, thien van, lieu va
gian cua » gian xu, ban cua
doc sach » hoc sach, toc sach, nuoc sach
phan dau » phan tu, hang dau
te sach » toc sach
va hanh » van hanh, va thanh, va danh
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu va
nang ma » tang ma, sang ma, nang cao
ma hoi » mai hoi, xa hoi, ma hoa
dau va » dau ve, lau va

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((te sach) or (doc sach)) ky nang ma hoi. ((hieu ve) OR (hieu van)) phan dau va hanh gian cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (doc sach)) ky nang ma hoi. ((hieu ve) OR (hieu van)) phan dau va hanh gian cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) or (doc sach)) ky nang ma hoi. ((hieu ve) OR (hieu van)) phan dau va hanh gian cua tre*".