Perhaps you should try some spelling variations:
hieu toan » bieu toan, thien toan, kiem toan
vu khach » vu khanh, vu khac, vay khach
cau tren » dau tren, ca tren, cau treo
khach ky » hanh ky, thanh ky
cau thuc » cau truc, cuu thuc, can thuc
toan cau » toan cao, toan ban, toan tap
lang xa » lang ha, dang xay, lang van
hanh va » hang va
ky lang » ky nang, ky dang, ky tang
cu tren » tu tren, dua tren

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

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