Perhaps you should try some spelling variations:
chat doc » chat hoc, chau doc, thuat doc
van hanh » van thanh, ban hanh, van anh
dang xay » dang van, van xay
te sach » toc sach
doi cua » dai cua, hoi cua
va hanh » va thanh, va danh, ban hanh
va chat » van chat, va phat, cao chat
hieu va » lieu va, hieu qua
nang xa » nang x, lang xa, nang ma
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: te sach y ((nang xa) or (dang xay)) hoi. hieu va chat doc ((va hanh) or (van hanh)) doi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach y ((nang xa) OR (dang xay)) hoi. hieu va chat doc ((va hanh) OR (van hanh)) doi cua tre.
• Adding a wildcard symbol may retrieve word variants: te sach y ((nang xa) or (dang xay)) hoi. hieu va chat doc ((va hanh) or (van hanh)) doi cua tre*.