Perhaps you should try some spelling variations:
danh kien » dinh kien, danh viet, linh kien
doc sach » hoc sach, toc sach, nuoc sach
kien cua » khien cua, dien cua, tien cua
thuc dan » thuc hanh, thuc vat
va cham » va chat, va tham
sach tu » sach thu, cach tu, sach ty
hieu va » lieu va, hieu qua
tu nang » tru nang, tu nong, tu nano
cua te » cua tu
x hoi » o hoi, x ho, 5 hoi

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc sach tu nang ((x hoi) or (xa hoi)). hieu va cham ((thuc dan) OR (hoc dan)) danh kien cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach tu nang ((x hoi) OR (xa hoi)). hieu va cham ((thuc dan) OR (hoc dan)) danh kien cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc sach tu nang ((x hoi) or (xa hoi)). hieu va cham ((thuc dan) OR (hoc dan)) danh kien cua te".
• Adding a wildcard symbol may retrieve word variants: doc sach tu nang ((x hoi) or (xa hoi)). hieu va cham ((thuc dan) OR (hoc dan)) danh kien cua te*.