Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
hieu cac » hieu luc, hieu va, hieu van
van hanh » van thanh, ban hanh, van anh
ha trung » he trung, ba trung, va trung
sach ty » sach y, sach tu, sach thu
va danh » va dinh, va dan, dia danh
va hanh » va thanh, ban hanh, dao hanh
ty nang » ky nang, ty xang, ty hang
cua tre » cua te, cuu tre, cua triet
cac ha » cac nha, cac ham, cac hat
nang o » nang co, nang ho, nang ro
o hoi » co hoi, o hoc, o hai

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 ty nang o hoi. hieu cac ha trung ((va danh) or (((va hanh) or (van hanh)))) dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ty nang o hoi. hieu cac ha trung ((va danh) OR (((va hanh) OR (van hanh)))) dai cua tre.
• Adding a wildcard symbol may retrieve word variants: thu sach ty nang o hoi. hieu cac ha trung ((va danh) or (((va hanh) or (van hanh)))) dai cua tre*.