Perhaps you should try some spelling variations:
cac thuc » cach thuc, cac thu, can thuc
dau tren » dau tien, dat tren, dau tieng
te sach » toc sach
sach ty » sach y, sach tu, sach thu
xang xa » lang xa, ang xa, dang xay
mang xa » lang xa, dang xay, mang cua
hieu ve » hieu va, hieu van
thuc va » thuc vat, thuc dan, thuc day
va luan » vay luan, van luan, va quan
luan vi » quan vi, luan va, luan ve
ve cac » va cac, vien cac
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 ty ((xang xa) or (((mang xa) OR (mang may)))) hoi. hieu ve cac thuc va luan vi dau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ty ((xang xa) OR (((mang xa) OR (mang may)))) hoi. hieu ve cac thuc va luan vi dau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ty ((xang xa) or (((mang xa) OR (mang may)))) hoi. hieu ve cac thuc va luan vi dau tren".
• Adding a wildcard symbol may retrieve word variants: te sach ty ((xang xa) or (((mang xa) OR (mang may)))) hoi. hieu ve cac thuc va luan vi dau tren*.