Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
hieu van » hieu va, thien van, lieu va
duc danh » duc anh, duc hanh, duc dan
duc manh » suc manh, duc anh, duc minh
cau tren » cu tren, dau tren, ca tren
hieu ve » hieu va
san cau » van cau, ban cau, can cau
y nang » ky nang, ly nang, v nang
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: thu sach y nang x hoi. ((hieu ve) or (hieu van)) cam ((duc danh) OR (duc manh)) thanh san cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach y nang x hoi. ((hieu ve) OR (hieu van)) cam ((duc danh) OR (duc manh)) thanh san cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach y nang x hoi. ((hieu ve) or (hieu van)) cam ((duc danh) OR (duc manh)) thanh san cau tren".
• Adding a wildcard symbol may retrieve word variants: thu sach y nang x hoi. ((hieu ve) or (hieu van)) cam ((duc danh) OR (duc manh)) thanh san cau tren*.