Perhaps you should try some spelling variations:
phuong dinh » phuong binh, phuong linh, phuong trinh
doi chieu » doc hieu, doi chi, mot chieu
hanh hang » thanh hang, hang hang, hanh han
dinh toan » tinh toan, hinh toan, minh toan
ho chieu » theo chieu, hoc thieu, mot chieu
cua bang » chua bang, cua ban, cua hang
cua dang » cua cong, cua ban
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: ((ho chieu) OR (doi chieu)) sach - hanh hang ((cua bang) or (cua dang)) phuong dinh toan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((ho chieu) OR (doi chieu)) sach - hanh hang ((cua bang) OR (cua dang)) phuong dinh toan cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((ho chieu) OR (doi chieu)) sach - hanh hang ((cua bang) or (cua dang)) phuong dinh toan cau".
• Adding a wildcard symbol may retrieve word variants: ((ho chieu) OR (doi chieu)) sach - hanh hang ((cua bang) or (cua dang)) phuong dinh toan cau*.