Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
van chat » cao chat
chat duc » chat xuc, chat doc, chet duoc
duc tuan » duc thuan, duc tan, duc toan
vu sach » vu bach, su sach, vu khach
te sach » toc sach
anh dai » vanh dai, anh bai, anh dat
cua tre » cuu tre, cua triet, dua tren
nang o » nang co, nang ho, nang ro
cua te » cua tu
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: ((vu sach) or (te sach)) ky nang o hoi. hieu van chat duc tuan anh dai ((cua tre) OR (cua te))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((vu sach) OR (te sach)) ky nang o hoi. hieu van chat duc tuan anh dai ((cua tre) OR (cua te)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((vu sach) or (te sach)) ky nang o hoi. hieu van chat duc tuan anh dai ((cua tre) OR (cua te))".
• Adding a wildcard symbol may retrieve word variants: ((vu sach) or (te sach)) ky nang o hoi. hieu van chat duc tuan anh dai ((cua tre) OR (cua te))*.