Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
van hanh » van thanh, ban hanh, van anh
thuc van » thuc vat, thuc dan, thuc va
cay thuc » cay thuoc, can thuc, day thuc
vien cay » vien cac, vien cao, vien xay
cua tre » cuu tre, cua triet, dua tren
sach tu » sach thu, cach tu, sach ty
vu sach » vu bach, su sach, vu khach
nang ma » tang ma, sang ma, nang cao
nang xa » nang x, lang xa, mang xa
cua te » cua tu

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu sach tu ((nang xa) OR (nang ma)) hoi. hieu vien cay thuc van hanh vi ((cua tre) or (cua te))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach tu ((nang xa) OR (nang ma)) hoi. hieu vien cay thuc van hanh vi ((cua tre) OR (cua te)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu sach tu ((nang xa) OR (nang ma)) hoi. hieu vien cay thuc van hanh vi ((cua tre) or (cua te))".
• Adding a wildcard symbol may retrieve word variants: vu sach tu ((nang xa) OR (nang ma)) hoi. hieu vien cay thuc van hanh vi ((cua tre) or (cua te))*.