Perhaps you should try some spelling variations:
danh kien » dinh kien, danh viet, linh kien
thuc day » thuc dan, thuc vat
kien cua » khien cua, dien cua, tien cua
hieu va » lieu va, hieu qua
va tham » van tham, va cham, va thanh
sach ky » sac ky, sach ty, sach kem
thuc va » thuc vat, thuc dan
nang xa » nang x, lang xa, nang ma
cua tre » cua te, cuu tre, cua triet

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 ky) OR (sach y)) nang xa hoi. hieu va tham ((thuc va) or (thuc day)) danh kien cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc ((sach ky) OR (sach y)) nang xa hoi. hieu va tham ((thuc va) OR (thuc day)) danh kien cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc ((sach ky) OR (sach y)) nang xa hoi. hieu va tham ((thuc va) or (thuc day)) danh kien cua tre".
• Adding a wildcard symbol may retrieve word variants: doc ((sach ky) OR (sach y)) nang xa hoi. hieu va tham ((thuc va) or (thuc day)) danh kien cua tre*.