Perhaps you should try some spelling variations:
cau theo » cau thi, cau tao
cau tren » cu tren, dau tren, ca tren
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
va hanh » van hanh, va thanh, va danh
te sach » toc sach
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
nang ma » tang ma, sang ma, nang cao
va dan » ca dan, va dao, va dau
ve cac » va cac, vien cac

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