Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
cau treo » cau theo, cau tren, cau triet
hieu ve » hieu va, hieu van
va hanh » van hanh, va thanh, va danh
nang ma » tang ma, sang ma, nang cao
cuu tre » cua tre, cau tren
ve cac » va cac, vien cac
va dan » ca dan, va dao, va dau
y nang » ky nang, ly nang, v nang

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 hoa. hieu ve cac nuoc ((va dan) or (va hanh)) doi ((cuu tre) or (cau treo))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach y nang ma hoa. hieu ve cac nuoc ((va dan) OR (va hanh)) doi ((cuu tre) OR (cau treo)).
• Adding a wildcard symbol may retrieve word variants: toc sach y nang ma hoa. hieu ve cac nuoc ((va dan) or (va hanh)) doi ((cuu tre) or (cau treo))*.