Perhaps you should try some spelling variations:
thien hach » thien thanh, hien hanh
hien sach » dien sach, kien sach, chieu sach
canh sinh » canh tinh, canh binh, tinh sinh
dung cong » dung trong
vat dung » van dung, va dung, viet dung
dan than » dan chan, ban than, van than
van tan » van tuan, van ban, van tai

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)) - canh sinh vat dung cong ((van tan) OR (dan than)) tap~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((hien sach) OR (thien hach)) - canh sinh vat dung cong ((van tan) or (dan than)) tap~".
• Adding a wildcard symbol may retrieve word variants: hoc ((hien sach) OR (thien hach)) - canh sinh vat dung cong ((van tan) or (dan than)) tap*.