Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
van hanh » van thanh, ban hanh, van anh
hieu va » lieu va, hieu qua
va danh » va dinh, va dan, va hanh
nang ma » tang ma, sang ma, nang cao
hai cua » thai cua, dai cua, hoi cua
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang
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: toc sach y nang ma hoi. hieu va ((pham duc) or (pham duy)) ((van hanh) or (va danh)) hai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach y nang ma hoi. hieu va ((pham duc) OR (pham duy)) ((van hanh) OR (va danh)) hai cua tre.
• Adding a wildcard symbol may retrieve word variants: toc sach y nang ma hoi. hieu va ((pham duc) or (pham duy)) ((van hanh) or (va danh)) hai cua tre*.