Perhaps you should try some spelling variations:
vat hanh » vat thanh, van hanh, va hanh
te sach » toc sach
sach tu » sach thu, cach tu, sach ty
tu nong » tu dong, tu cong, tu tong
nong xa » song xa, dong xa, nong va
hieu va » lieu va, hieu qua
co thuc » co thua, mo thuc, so thuc
do thuc » hoc thuc, dan thuc
vai cua » dai cua, hai cua, bai cua
lai cua » dai cua, hai cua, lai chau

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 tu nong xa hoi. hieu va ((co thuc) OR (do thuc)) vat hanh ((vai cua) or (lai cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach tu nong xa hoi. hieu va ((co thuc) OR (do thuc)) vat hanh ((vai cua) OR (lai cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach tu nong xa hoi. hieu va ((co thuc) OR (do thuc)) vat hanh ((vai cua) or (lai cua)) tre".
• Adding a wildcard symbol may retrieve word variants: te sach tu nong xa hoi. hieu va ((co thuc) OR (do thuc)) vat hanh ((vai cua) or (lai cua)) tre*.