Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac, hoc anh
va hanh » van hanh, va thanh, va danh
sach ty » sach y, sach tu, sach thu
cuu tre » cua tre, cau tren, cau treo
nang xa » nang x, nang ma, mang xa
lang xa » lang ha, dang xay, lang van
va cao » va cac, va co, va dao
tuc va » thuc va, truc va, tuc xa
vi cuu » vi luu, vinh cuu
va cam » va cham, va cac, va cai

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc sach ty ((nang xa) or (lang xa)) hoi. hieu ((va cam) OR (va cao)) tuc va hanh vi cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc sach ty ((nang xa) OR (lang xa)) hoi. hieu ((va cam) OR (va cao)) tuc va hanh vi cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc sach ty ((nang xa) or (lang xa)) hoi. hieu ((va cam) OR (va cao)) tuc va hanh vi cuu tre".
• Adding a wildcard symbol may retrieve word variants: hoc sach ty ((nang xa) or (lang xa)) hoi. hieu ((va cam) OR (va cao)) tuc va hanh vi cuu tre*.