Perhaps you should try some spelling variations:
sach cay » sach cap, sach hay, sach nay
truc van » truc va, truc ban, truc dan
thuc van » thuc vat, thuc dan, thuc va
dau tren » dau tien, dat tren, dau tieng
te sach » toc sach
mang xa » lang xa, dang xay, mang cua
hieu va » lieu va, hieu qua
va cau » van cau, va cac, va dau
vi dau » vi dai, va dau, bi dau

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

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