Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
nam thuc » nam thuoc, am thuc, nam thu
vat hanh » vat thanh, van hanh, va hanh
ban hanh » ban hang
cau tren » cu tren, dau tren, ca tren
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
cuu tre » cua tre, cau treo
x hoi » xa hoi, o hoi, x ho

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 nang x hoi. hieu van nam thuc ((vat hanh) or (ban hanh)) vi ((cuu tre) OR (cau tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang x hoi. hieu van nam thuc ((vat hanh) OR (ban hanh)) vi ((cuu tre) OR (cau tren)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang x hoi. hieu van nam thuc ((vat hanh) or (ban hanh)) vi ((cuu tre) OR (cau tren))".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang x hoi. hieu van nam thuc ((vat hanh) or (ban hanh)) vi ((cuu tre) OR (cau tren))*.