Perhaps you should try some spelling variations:
hieu toan » bieu toan, thien toan, kiem toan
toan cau » toan cao, toan ban, toan tap
cau thuc » cau truc, cuu thuc, can thuc
vat hanh » vat thanh, van hanh, va hanh
cau tren » dau tren, ca tren, cau treo
ky lang » ky nang, ky dang, ky tang
lang xa » lang ha, dang xay, lang van
hanh va » hang va, hanh vi
cu tren » tu tren, dua tren
su sac » su sach, su cac, su xac
sac ky » cac ky, sai ky

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sac ky lang xa hoi. hieu toan cau thuc vat hanh va ((cau tren) or (cu tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sac ky lang xa hoi. hieu toan cau thuc vat hanh va ((cau tren) OR (cu tren)).
• Adding a wildcard symbol may retrieve word variants: su sac ky lang xa hoi. hieu toan cau thuc vat hanh va ((cau tren) or (cu tren))*.