Perhaps you should try some spelling variations:
cac thuc » cach thuc, cac thu, can thuc
cau tren » cu tren, dau tren, ca tren
sach ky » sach y, sach ty, sach kem
nang xa » nang x, nang ma, mang xa
lang xa » lang ha, dang xay, lang van
thuc va » thuc vat, thuc dan, thuc day
dau thi » cau thi, dan thi, dao thi
thi cau » thi chau, thi cu, thi cam
sac ky » cac ky, sai ky
va dau » va dao

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu ((sach ky) or (sac ky)) ((nang xa) OR (lang xa)) hoi. lieu va cac thuc va dau thi cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ky) OR (sac ky)) ((nang xa) OR (lang xa)) hoi. lieu va cac thuc va dau thi cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ky) or (sac ky)) ((nang xa) OR (lang xa)) hoi. lieu va cac thuc va dau thi cau tren".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ky) or (sac ky)) ((nang xa) OR (lang xa)) hoi. lieu va cac thuc va dau thi cau tren*.