Perhaps you should try some spelling variations:
nhung cong » thong cong, hang cong, nhung don
quang toan » quang tuan, quang tran, quang doan
tieu sach » chieu sach, dien sach, te sach
dung cong » dung trong
toan cao » toan ban, toan tap
mang va » mang vua, hang va, dang va
bang va » hang va, ban va, trang va

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

• If you are trying to use Boolean operators, they must be ALL CAPS: theo tieu sach - hanh ((mang va) OR (bang va)) ((nhung cong) OR (dung cong)) quang toan cao~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "theo tieu sach - hanh ((mang va) or (bang va)) ((nhung cong) OR (dung cong)) quang toan cao~".
• Adding a wildcard symbol may retrieve word variants: theo tieu sach - hanh ((mang va) or (bang va)) ((nhung cong) OR (dung cong)) quang toan cao*.