Perhaps you should try some spelling variations:
ngan thanh » nganh thanh, ngon thanh, nhan thanh
ngan hanh » ngan hang, ngan danh, ngan han
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, su sach, tu cach
van cau » van dau, van hau, van chat
xang xa » lang xa, mang xa, ang xa
te sach » toc sach
ca tren » cau tren, cu tren, la tren
vi ca » vit ca, li ca, va ca

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) or (te sach)) ty xang xa hoi. hieu van cau truc ((ngan hanh) OR (ngan thanh)) vi ca tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (te sach)) ty xang xa hoi. hieu van cau truc ((ngan hanh) OR (ngan thanh)) vi ca tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (te sach)) ty xang xa hoi. hieu van cau truc ((ngan hanh) OR (ngan thanh)) vi ca tren".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (te sach)) ty xang xa hoi. hieu van cau truc ((ngan hanh) OR (ngan thanh)) vi ca tren*.