Perhaps you should try some spelling variations:
sach tranh » canh tranh
theo hieu » theo chieu, theo tieu, thien hieu
hieu lang » chieu sang, hieu quang, nhieu tang
cach manh » cach mang, cach nhanh, sach danh
dung cong » dung trong
gian thua » giai thuat, gian ha, gian phu
qua dung » quang dung, su dung, qua song
cong tan » cong tac, cong san, cong thanh
gian cua » gian xu, ban cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: theo hieu lang - ((cach manh) or (sach tranh)) qua dung cong tan ((gian thua) OR (gian cua))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: theo hieu lang - ((cach manh) OR (sach tranh)) qua dung cong tan ((gian thua) OR (gian cua)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "theo hieu lang - ((cach manh) or (sach tranh)) qua dung cong tan ((gian thua) OR (gian cua))".
• Adding a wildcard symbol may retrieve word variants: theo hieu lang - ((cach manh) or (sach tranh)) qua dung cong tan ((gian thua) OR (gian cua))*.