Perhaps you should try some spelling variations:
ngang toan » dang toan, quang toan
nganh toan » nganh thanh, thanh toan, manh toan
hieu lang » chieu sang, hieu quang, nhieu tang
trinh cua » trinh luat, trinh quan, trinh luan
dung cong » dung trong
tinh cua » sinh cua, tinh chat, tranh cua
ho hieu » ho chieu, hoi hieu, nho hieu

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

• Performing a fuzzy search may retrieve terms with similar spellings: ho hieu lang - hanh ((trinh cua) OR (tinh cua)) dung cong ((ngang toan) or (nganh toan)) cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ho hieu lang - hanh ((trinh cua) OR (tinh cua)) dung cong ((ngang toan) OR (nganh toan)) cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "ho hieu lang - hanh ((trinh cua) OR (tinh cua)) dung cong ((ngang toan) or (nganh toan)) cau".
• Adding a wildcard symbol may retrieve word variants: ho hieu lang - hanh ((trinh cua) OR (tinh cua)) dung cong ((ngang toan) or (nganh toan)) cau*.