Perhaps you should try some spelling variations:
vat thanh » dat thanh, gat thanh, tat thanh
cua triet » cua viet, su triet, va triet
thu sach » tu sach, thuat sach, thuoc sach
hieu van » thien van, lieu va, hieu ve
nam thuc » nam thuoc, am thuc, nam thu
thanh do » thanh de, thanh pho, thanh hoa
hieu va » lieu va, hieu qua
y nang » ky nang, ly nang, v nang
do cua » doi cua, co cua, de cua
x hoi » xa hoi, o hoi, 5 hoi

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) OR (x ho)). ((hieu van) or (hieu va)) nam thuc vat thanh do cua triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach y nang ((x hoi) OR (x ho)). ((hieu van) OR (hieu va)) nam thuc vat thanh do cua triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach y nang ((x hoi) OR (x ho)). ((hieu van) or (hieu va)) nam thuc vat thanh do cua triet".
• Adding a wildcard symbol may retrieve word variants: thu sach y nang ((x hoi) OR (x ho)). ((hieu van) or (hieu va)) nam thuc vat thanh do cua triet*.