Perhaps you should try some spelling variations:
thien hach » thien thanh, hien hanh
thieu sach » chieu sach, hieu cach, thieu cac
hanh trang » thanh trung, canh tranh, hanh trinh
nhung cong » dung cong, thong cong, hang cong
trinh toan » tinh toan, thanh toan, trinh han
theo sach » thuoc sach, te sach, theo lich
trang va » tran van, hang va
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: hoc ((((thieu sach) OR (theo sach))) or (thien hach)) - hanh trang va nhung cong trinh toan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((((thieu sach) OR (theo sach))) OR (thien hach)) - hanh trang va nhung cong trinh toan cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((((thieu sach) OR (theo sach))) or (thien hach)) - hanh trang va nhung cong trinh toan cau".
• Adding a wildcard symbol may retrieve word variants: hoc ((((thieu sach) OR (theo sach))) or (thien hach)) - hanh trang va nhung cong trinh toan cau*.