Perhaps you should try some spelling variations:
thien van » thi van
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, lieu va, hieu ve
xay hang » xay dung, ban hang, ly hang
chat tu » nhat tu, chai tu, chay tu
dau tre » dau tren, dau tien, cau tren
y nang » ky nang, ly nang, v nang
va dau » va dao

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 x ho. ((hieu van) or (thien van)) chat tu xay hang va dau tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach y nang x ho. ((hieu van) OR (thien van)) chat tu xay hang va dau tre.
• Adding a wildcard symbol may retrieve word variants: toc sach y nang x ho. ((hieu van) or (thien van)) chat tu xay hang va dau tre*.