Perhaps you should try some spelling variations:
nam duoc » nam thuoc, da duoc, dat duoc
tan hanh » tan thanh, tang hanh, toan hanh
dang xay » dang van, van xay
duoc tan » duc tan, duoc ban, duoc dan
hieu van » hieu va, thien van, hieu ve
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
xay hoi » xa hoi, tay hoi, cay phoi
ky dang » ky nang, ky danh
vi cau » ve cau, di cau, viet cau
va cau » van cau, va cac, va dau

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ky dang xay hoi. ((hieu van) or (lieu va)) nam duoc tan hanh ((vi cau) or (va cau)) trieu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky dang xay hoi. ((hieu van) OR (lieu va)) nam duoc tan hanh ((vi cau) OR (va cau)) trieu.
• Adding a wildcard symbol may retrieve word variants: tu sach ky dang xay hoi. ((hieu van) or (lieu va)) nam duoc tan hanh ((vi cau) or (va cau)) trieu*.