Perhaps you should try some spelling variations:
tham thuc » nham thuc, pham thuc, tam thuc
dang xay » dang van, van xay
va dinh » van dinh, va kinh, va tinh
va danh » va dan, va hanh, dia danh
va tham » van tham, va cham, va thanh
sach ky » sac ky, sach ty, sach kem
hieu va » lieu va, hieu qua
xay hoi » xa hoi, tay hoi, cay phoi
cua tre » cua te, cuu tre, cua triet

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

• Performing a fuzzy search may retrieve terms with similar spellings: su ((sach ky) or (sach y)) dang xay hoi. hieu va tham thuc ((va danh) OR (va dinh)) dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ky) OR (sach y)) dang xay hoi. hieu va tham thuc ((va danh) OR (va dinh)) dai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach ky) or (sach y)) dang xay hoi. hieu va tham thuc ((va danh) OR (va dinh)) dai cua tre".
• Adding a wildcard symbol may retrieve word variants: su ((sach ky) or (sach y)) dang xay hoi. hieu va tham thuc ((va danh) OR (va dinh)) dai cua tre*.