Perhaps you should try some spelling variations:
chieu sach » chinh sach, chiet tach, chieu sang
thong cong » trong cong, tong cong, thong thong
hieu lang » chieu sang, hieu quang, nhieu tang
hang hoc » hang hoa, nang hoc, bang hoc
nang doc » nang luc
cong tap » cuong tap, cong tac, cong tan
tap dan » tap doan, tap danh, tap van
dan dat » dung dat, dong dat, dinh dat

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

• Performing a fuzzy search may retrieve terms with similar spellings: theo ((chieu sach) or (hieu lang)) - hanh ((hang hoc) or (nang doc)) thong cong tap dan dat~.
• If you are trying to use Boolean operators, they must be ALL CAPS: theo ((chieu sach) OR (hieu lang)) - hanh ((hang hoc) OR (nang doc)) thong cong tap dan dat.
• Adding a wildcard symbol may retrieve word variants: theo ((chieu sach) or (hieu lang)) - hanh ((hang hoc) or (nang doc)) thong cong tap dan dat*.