Perhaps you should try some spelling variations:
dau tieng » dau tien, cau tieng, day tieng
sach thu » sach thue, sach thieu, sach tham
thu nang » thi nang, thu hang, thu bang
van hanh » van thanh, ban hanh, van anh
te sach » toc sach
nang xa » nang x, lang xa, nang ma
hieu va » lieu va
va hanh » va thanh, va danh, ban hanh
cam tu » cam thu, nam tu, dam tu

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 thu nang xa hoi. ((hieu va) or (hieu qua)) cam tu ((va hanh) OR (van hanh)) bi dau tieng~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach thu nang xa hoi. ((hieu va) OR (hieu qua)) cam tu ((va hanh) OR (van hanh)) bi dau tieng.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach thu nang xa hoi. ((hieu va) or (hieu qua)) cam tu ((va hanh) OR (van hanh)) bi dau tieng".
• Adding a wildcard symbol may retrieve word variants: te sach thu nang xa hoi. ((hieu va) or (hieu qua)) cam tu ((va hanh) OR (van hanh)) bi dau tieng*.