Perhaps you should try some spelling variations:
dang xay » dang van, van xay
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
dinh vi » dinh ve, dinh viet, dinh tri
va dinh » van dinh, va kinh, va tinh
cac toc » cac toi, cac thoi
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu va, hieu van
lang xa » lang ha, lang van
vi cua » vai cua, di cua

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) or (lang xa)) hoi. hieu ve ((cac toc) OR (cac nuoc)) va dinh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((dang xay) OR (lang xa)) hoi. hieu ve ((cac toc) OR (cac nuoc)) va dinh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky ((dang xay) or (lang xa)) hoi. hieu ve ((cac toc) OR (cac nuoc)) va dinh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((dang xay) or (lang xa)) hoi. hieu ve ((cac toc) OR (cac nuoc)) va dinh vi cua tre*.