Perhaps you should try some spelling variations:
thong cong » trong cong, tong cong, thong thong
hieu lang » chieu sang, hieu quang, nhieu tang
trinh cua » trinh luat, trinh quan, trinh luan
trinh van » trinh quan, trinh toan, dinh van
trinh han » trinh quan
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 ((tinh cua) or (trinh cua)) thong cong ((trinh van) OR (trinh han)) dau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ho hieu lang - hanh ((tinh cua) OR (trinh cua)) thong cong ((trinh van) OR (trinh han)) dau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "ho hieu lang - hanh ((tinh cua) or (trinh cua)) thong cong ((trinh van) OR (trinh han)) dau".
• Adding a wildcard symbol may retrieve word variants: ho hieu lang - hanh ((tinh cua) or (trinh cua)) thong cong ((trinh van) OR (trinh han)) dau*.