Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
thai cua » than cua, tai cuc, tri cua
van hanh » van thanh, ban hanh, van anh
va hanh » va thanh, va danh, ban hanh
van bac » van ban, van bao, van hac
so sach » so sanh, bo sach, co sach
sach ky » sac ky, sach y, sach ty
nang ma » tang ma, sang ma, nang cao
nang xa » nang x, lang xa, mang xa
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 ((nang xa) OR (nang ma)) hoi. hieu van bac xuc ((va hanh) or (van hanh)) thai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ky ((nang xa) OR (nang ma)) hoi. hieu van bac xuc ((va hanh) OR (van hanh)) thai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ky ((nang xa) OR (nang ma)) hoi. hieu van bac xuc ((va hanh) or (van hanh)) thai cua tre".
• Adding a wildcard symbol may retrieve word variants: so sach ky ((nang xa) OR (nang ma)) hoi. hieu van bac xuc ((va hanh) or (van hanh)) thai cua tre*.