Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
hieu van » hieu va, thien van, lieu va
dang xay » dang van, van xay
nam thuc » nam thuoc, am thuc, nam thu
dinh ke » dinh ket, dinh ve, dinh le
va dinh » van dinh, va kinh, va tinh
sach ky » sac ky, sach ty, sach kem
xay hoi » xa hoi, tay hoi, cay phoi
nam duc » nam duoc, pham duc, nam buoc
ke cau » ket cau

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

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