Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
va hanh » van hanh, va thanh, va danh
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, mang xa
nang ma » tang ma, sang ma, nang cao
cua tre » cua te, cuu tre, cua triet
ve cao » va cao, ve cac, ve co
ve bao » te bao, va bao
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: thu sach ky ((nang xa) or (nang ma)) hoi. hieu ((ve cao) OR (ve bao)) duc va hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky ((nang xa) OR (nang ma)) hoi. hieu ((ve cao) OR (ve bao)) duc va hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ky ((nang xa) or (nang ma)) hoi. hieu ((ve cao) OR (ve bao)) duc va hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: thu sach ky ((nang xa) or (nang ma)) hoi. hieu ((ve cao) OR (ve bao)) duc va hanh vi cua tre*.