Perhaps you should try some spelling variations:
va trien » va truyen, va thiet, va tuyen
cac thuc » cach thuc, cac thu, can thuc
va triet » va thiet, ve triet, cua triet
dang hai » dang khai, hang hai, dung hai
van hanh » van thanh, ban hanh, van anh
dang xay » dang van, van xay
hieu va » lieu va, hieu qua
xay hoi » xa hoi, tay hoi, cay phoi
thuc va » thuc vat, thuc dan, thuc day
sach ky » sac ky, sach y, sach ty
ky dang » ky nang, ky danh
te sach » toc sach

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ky dang xay hoi. hieu va cac thuc va ((van hanh) OR (dang hai)) ((va triet) OR (va trien))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ky dang xay hoi. hieu va cac thuc va ((van hanh) or (dang hai)) ((va triet) OR (va trien))~".
• Adding a wildcard symbol may retrieve word variants: te sach ky dang xay hoi. hieu va cac thuc va ((van hanh) or (dang hai)) ((va triet) OR (va trien))*.