Perhaps you should try some spelling variations:
thong cong » trong cong, tong cong, thong thong
hieu lang » chieu sang, hieu quang, nhieu tang
hanh sinh » hanh tinh, hanh dinh, hinh sinh
dang cong » dung cong
trinh han » trinh quan
doi hieu » doi chieu, doc hieu, doi hien
sinh va » sinh vat, tinh va, dinh van
han dau » hang dau, phan dau, van dau

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

• Performing a fuzzy search may retrieve terms with similar spellings: doi hieu lang - hanh sinh va ((thong cong) or (dang cong)) trinh han dau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doi hieu lang - hanh sinh va ((thong cong) OR (dang cong)) trinh han dau*.