Perhaps you should try some spelling variations:
cau thuc » cau truc, cuu thuc, can thuc
thuc van » thuc vat, thuc dan, thuc va
van hanh » van thanh, ban hanh, van anh
cua viet » ca viet, hoa viet, cua vat
sach ty » sach y, sach tu, sach thu
nang xa » nang x, lang xa, nang ma
hieu va » lieu va, hieu qua
hanh va » hang va, hanh vi
sai ky » sac ky
va cau » van cau, va cac, va dau
va cua » va chua, via cua, ca cua

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 ty) or (sai ky)) nang xa hoi. hieu va cau thuc van hanh va cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ty) OR (sai ky)) nang xa hoi. hieu va cau thuc van hanh va cua viet.
• Adding a wildcard symbol may retrieve word variants: tu ((sach ty) or (sai ky)) nang xa hoi. hieu va cau thuc van hanh va cua viet*.