Perhaps you should try some spelling variations:
thien van » thi van
hieu van » hieu va, lieu va, hieu ve
tan hanh » tan thanh, tang hanh, toan hanh
hanh dai » hanh tai, hanh dao, vanh dai
sach ky » sac ky, sach y, sach ty
nang ma » tang ma, sang ma, nang cao
cam duc » cam xuc, cao duc, pham duc
cua tre » cua te, cuu tre, cua triet
ma hoi » mai hoi, xa hoi, ma hoa

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

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