Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
duoc van » duoc va, duc van, duoc ban
hanh di » hanh vi, hanh de, hang di
sach ky » sac ky, sach y, sach ty
cua tre » cua te, cuu tre, cua triet
nang ma » tang ma, sang ma, nang cao
ma hoi » mai hoi, xa hoi, ma hoa
ve bao » te bao, va bao
sai ky » sac ky
di cua » dai cua, doi cua, de cua
ve tao » de tao, ve tac, ve tai

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu ((sach ky) or (sai ky)) nang ma hoi. hieu ((ve tao) OR (ve bao)) duoc van hanh di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu ((sach ky) OR (sai ky)) nang ma hoi. hieu ((ve tao) OR (ve bao)) duoc van hanh di cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu ((sach ky) or (sai ky)) nang ma hoi. hieu ((ve tao) OR (ve bao)) duoc van hanh di cua tre".
• Adding a wildcard symbol may retrieve word variants: thu ((sach ky) or (sai ky)) nang ma hoi. hieu ((ve tao) OR (ve bao)) duoc van hanh di cua tre*.