Perhaps you should try some spelling variations:
thien van » thi van
ban hanh » ban hang
cua tre » cua te, cua triet, dua tren
sach ty » sach y, sach tu, sach thu
tu sach » thu sach, su sach, te sach
nang xa » nang x, lang xa, mang xa
nang ma » tang ma, sang ma, nang cao
cuu tre » cau tren, cau treo
nam ma » nam mua, nam a, nam va
ma ban » mua ban, va ban, ma van

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 ty ((nang xa) or (nang ma)) hoi. thien van nam ma ban hanh vi ((cua tre) OR (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty ((nang xa) OR (nang ma)) hoi. thien van nam ma ban hanh vi ((cua tre) OR (cuu tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty ((nang xa) or (nang ma)) hoi. thien van nam ma ban hanh vi ((cua tre) OR (cuu tre))".
• Adding a wildcard symbol may retrieve word variants: tu sach ty ((nang xa) or (nang ma)) hoi. thien van nam ma ban hanh vi ((cua tre) OR (cuu tre))*.