Perhaps you should try some spelling variations:
thien hach » thien thanh, hien hanh
trung tuan » trung thanh, trung tam, tran tuan
nhung cong » dung cong, thong cong, hang cong
hien sach » dien sach, kien sach, chieu sach
tang cua » mang cua, hang cua, tang luan
cong tac » cong ty
tac toan » tap toan, tam toan, hach toan
toan cau » toan cao, toan ban, toan tap

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: hoc ((hien sach) OR (thien hach)) - hanh ((trung tuan) OR (tang cua)) nhung cong tac toan cau~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((hien sach) OR (thien hach)) - hanh ((trung tuan) or (tang cua)) nhung cong tac toan cau~".
• Adding a wildcard symbol may retrieve word variants: hoc ((hien sach) OR (thien hach)) - hanh ((trung tuan) or (tang cua)) nhung cong tac toan cau*.