Perhaps you should try some spelling variations:
thieu sach » chieu sach, thien hach, theo sach
canh trinh » canh tranh, hanh trinh, canh tinh
hieu cach » hieu cac, chieu sach, hieu ca
dang cong » dung cong
trinh va » trinh van, trinh vat, trinh ve
cong tan » cong tac, cong san, cong thanh
than cap » khan cap, thanh lap, thanh cac
toan cau » toan cao, toan ban, toan tap
va dang » van dang, va nang, va lang

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc ((thieu sach) OR (hieu cach)) - canh trinh va dang cong tan ((than cap) or (toan cau))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc ((thieu sach) OR (hieu cach)) - canh trinh va dang cong tan ((than cap) OR (toan cau)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc ((thieu sach) OR (hieu cach)) - canh trinh va dang cong tan ((than cap) or (toan cau))".
• Adding a wildcard symbol may retrieve word variants: toc ((thieu sach) OR (hieu cach)) - canh trinh va dang cong tan ((than cap) or (toan cau))*.