Perhaps you should try some spelling variations:
vat hanh » vat thanh, van hanh, nhat hanh
cac thuc » cach thuc, cac thu, can thuc
su sach » so sach, vu sach
tai cuu » tai cuc, tai buu, tai cua
va hanh » van hanh, va thanh, va danh
hieu va » lieu va, hieu qua
hang ca » hang va, nang cao, hang tai
lang xa » lang ha, dang xay, lang van
cuu tre » cua tre, cau tren, cau treo

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach y ((lang xa) or (hang ca)) hoi. hieu va cac thuc ((vat hanh) OR (va hanh)) tai cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach y ((lang xa) OR (hang ca)) hoi. hieu va cac thuc ((vat hanh) OR (va hanh)) tai cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach y ((lang xa) or (hang ca)) hoi. hieu va cac thuc ((vat hanh) OR (va hanh)) tai cuu tre".
• Adding a wildcard symbol may retrieve word variants: su sach y ((lang xa) or (hang ca)) hoi. hieu va cac thuc ((vat hanh) OR (va hanh)) tai cuu tre*.