Perhaps you should try some spelling variations:
nang doi » nang doc, hang doi, nang dong
nang noi » nang doc
te sach » toc sach
ky lang » ky nang, ky dang, tay lang
ky tang » ky nang, ky dang, kho tang
hieu ve » hieu va, hieu van
cac tuc » cac toc, cac tu, cac tac
ve cac » va cac, vien cac
thiet » thieu

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

• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ((ky lang) OR (ky tang)) xa hoi. hieu ve cac tuc xa ((nang doi) OR (nang noi)) va thiet~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ((ky lang) OR (ky tang)) xa hoi. hieu ve cac tuc xa ((nang doi) or (nang noi)) va thiet~".
• Adding a wildcard symbol may retrieve word variants: te sach ((ky lang) OR (ky tang)) xa hoi. hieu ve cac tuc xa ((nang doi) or (nang noi)) va thiet*.