Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
nhanh ha » thanh hoa, thanh hai, khanh hoa
hanh hai » thanh hai, nhanh hai, hang hai
dang xay » dang van, van xay
van bac » van ban, van bao, van hac
so sach » so sanh, bo sach, co sach
sach ky » sac ky, sach y, sach ty
lang xa » lang ha, lang van
cua tre » cua te, cuu tre, cua triet

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach ky ((lang xa) OR (dang xay)) hoi. hieu van bac duc va ((hanh hai) or (nhanh ha)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ky ((lang xa) OR (dang xay)) hoi. hieu van bac duc va ((hanh hai) OR (nhanh ha)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ky ((lang xa) OR (dang xay)) hoi. hieu van bac duc va ((hanh hai) or (nhanh ha)) cua tre".
• Adding a wildcard symbol may retrieve word variants: so sach ky ((lang xa) OR (dang xay)) hoi. hieu van bac duc va ((hanh hai) or (nhanh ha)) cua tre*.