Perhaps you should try some spelling variations:
phuong hinh » phuong binh, phuong linh, phuong dinh
theo chieu » theo tieu, ho chieu, theo chu
chieu sach » chinh sach, chiet tach, chieu sang
hanh hang » thanh hang, hang hang, hanh han
hinh toan » tinh toan, thanh toan, trinh toan
cua bang » chua bang, cua hang, cua banh
cua dang » cua cong
toan cau » toan cao, toan ban, toan tap

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 - hanh hang ((((cua bang) OR (cua ban))) or (cua dang)) phuong hinh toan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: theo chieu sach - hanh hang ((((cua bang) OR (cua ban))) OR (cua dang)) phuong hinh toan cau*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "theo chieu sach - hanh hang ((((cua bang) OR (cua ban))) or (cua dang)) phuong hinh toan cau*".