Perhaps you should try some spelling variations:
sach nuoc » sach duoc, bach tuoc, dich nuoc
hieu viec » nhieu viec, sieu viet, hieu hien
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
cuu tre » cua tre, cau tren, cau treo
doi cuu » doi cua, doi cuoc
dan doi » dan hoi, dan toi, van doi
nang ma » tang ma, sang ma, nang cao
hieu ve » hieu va, hieu van
sac ky » cac ky, sai ky
va dan » ca dan, va dao, va dau
ma hoi » mai hoi, xa hoi, ma hoa
so sac » so sach, so dac

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sac ky nang ma hoi. ((hieu viec) or (hieu ve)) ((sach nuoc) or (cac nuoc)) va dan doi cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sac ky nang ma hoi. ((hieu viec) OR (hieu ve)) ((sach nuoc) OR (cac nuoc)) va dan doi cuu tre.
• Adding a wildcard symbol may retrieve word variants: so sac ky nang ma hoi. ((hieu viec) or (hieu ve)) ((sach nuoc) or (cac nuoc)) va dan doi cuu tre*.