Perhaps you should try some spelling variations:
thuat sach » thuat lanh, thuat san
van hanh » van thanh, ban hanh, van anh
hieu van » hieu va, thien van, lieu va
va hanh » va thanh, va danh, ban hanh
tai cua » thai cua, tai cuc, tri cua
van hai » van ha, van chat, van phan
cua tre » cua te, cuu tre, cua triet
hai du » hai vu, tai du, hai di
xang x » nang x
x hoi » xa hoi, o hoi, x ho

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((thu hoach) or (thuat sach)) ty xang x hoi. hieu van hai du ((va hanh) OR (van hanh)) tai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thu hoach) OR (thuat sach)) ty xang x hoi. hieu van hai du ((va hanh) OR (van hanh)) tai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((thu hoach) or (thuat sach)) ty xang x hoi. hieu van hai du ((va hanh) OR (van hanh)) tai cua tre".
• Adding a wildcard symbol may retrieve word variants: ((thu hoach) or (thuat sach)) ty xang x hoi. hieu van hai du ((va hanh) OR (van hanh)) tai cua tre*.