Perhaps you should try some spelling variations:
canh trinh » canh tranh, hanh trinh, canh tinh
duong cong » dung cong, duong trong, trong cong
luong cong » dung cong, trong cong, cong cong
hoc chieu » hoc thieu, hoc hien, hoc dieu
ho chieu » theo chieu, hoc thieu, doi chieu
trinh va » trinh van, trinh vat, trinh ve
dung von » dong von, dung cong, dung va
von ban » von bang, van ban, con ban

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((hoc chieu) or (ho chieu)) xanh - canh trinh va ((duong cong) OR (luong cong)) dung von ban~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((hoc chieu) OR (ho chieu)) xanh - canh trinh va ((duong cong) OR (luong cong)) dung von ban.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((hoc chieu) or (ho chieu)) xanh - canh trinh va ((duong cong) OR (luong cong)) dung von ban".
• Adding a wildcard symbol may retrieve word variants: ((hoc chieu) or (ho chieu)) xanh - canh trinh va ((duong cong) OR (luong cong)) dung von ban*.