Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, hieu ve
van hanh » van thanh, ban hanh, van anh
hanh vai » hanh vi, hanh va, hanh tai
nang ma » tang ma, sang ma, nang cao
cam duc » cam xuc, cao duc, pham duc
duc van » duc va, duc tan, duc manh
vai cua » dai cua, hai cua, lai cua
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: ((te sach) or (toc sach)) ky nang ma hoa. ((hieu van) or (lieu va)) cam duc van hanh vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) ky nang ma hoa. ((hieu van) OR (lieu va)) cam duc van hanh vai cua tre.
• Adding a wildcard symbol may retrieve word variants: ((te sach) or (toc sach)) ky nang ma hoa. ((hieu van) or (lieu va)) cam duc van hanh vai cua tre*.