Perhaps you should try some spelling variations:
khung hoang » phuong hoang
chieu sach » chinh sach, chiet tach, chieu sang
doanh khoa » toan khoa
hieu lang » chieu sang, hieu quang, nhieu tang
doanh hua » doanh cua, doanh ha, doanh luan
hoang van » hang va
van tuan » van quan, van ban, anh tuan
tuan ban » tuan bang, toan ban, luan ban

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) or (chieu sach)) - hanh ((doanh hua) OR (doanh khoa)) khung hoang van tuan ban~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doi ((hieu lang) OR (chieu sach)) - hanh ((doanh hua) OR (doanh khoa)) khung hoang van tuan ban*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doi ((hieu lang) or (chieu sach)) - hanh ((doanh hua) OR (doanh khoa)) khung hoang van tuan ban*".