Perhaps you should try some spelling variations:
tham thuc » nham thuc, pham thuc, tam thuc
toc sach » hoc sach, doc sach, thuoc sach
van dinh » van minh, van dich, va dinh
vai cua » dai cua, hai cua, lai cua
va hanh » van hanh, va thanh, va danh
va tham » van tham, va cham, va thanh
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang
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: toc sach y nang o hoi. hieu va tham thuc ((((va hanh) or (dia ban))) or (van dinh)) vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach y nang o hoi. hieu va tham thuc ((((va hanh) OR (dia ban))) OR (van dinh)) vai cua tre.
• Adding a wildcard symbol may retrieve word variants: toc sach y nang o hoi. hieu va tham thuc ((((va hanh) or (dia ban))) or (van dinh)) vai cua tre*.