Perhaps you should try some spelling variations:
hieu thien » hieu hien, chieu chien, dieu khien
thien cac » hien cac, thien cau, thieu cac
va triet » va thiet, va trien, ve triet
cau tren » cu tren, dau tren, ca tren
sach ky » sac ky, sach y, sach ty
cuu tre » cua tre, cau treo
tinh va » tich va, trinh van, trinh vat
tu sach » thu sach, su sach, te sach
cac lao » ca lao, cac loai, cac giao
xay hoi » xa hoi, tay hoi, cay phoi
va tinh » may tinh
lao va » tao va, cao va, bao va
ky van » ly van, ty van, ky va

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 van xay hoi. hieu thien cac lao va tinh va ((((cuu tre) OR (cau tren))) or (va triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky van xay hoi. hieu thien cac lao va tinh va ((((cuu tre) OR (cau tren))) OR (va triet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky van xay hoi. hieu thien cac lao va tinh va ((((cuu tre) OR (cau tren))) or (va triet))".
• Adding a wildcard symbol may retrieve word variants: tu sach ky van xay hoi. hieu thien cac lao va tinh va ((((cuu tre) OR (cau tren))) or (va triet))*.