Perhaps you should try some spelling variations:
toc sach » hoc sach, thuoc sach, nuoc sach
doc sach » hoc sach, nuoc sach, dac sac
co thuc » do thuc, co thua, mo thuc
lai cua » dai cua, hai cua, lai chau
vai cua » dai cua, hai cua, bai cua
va danh » va dinh, va dan, va hanh
thuc va » thuc vat, thuc dan, thuc day
hieu va » lieu va, hieu qua
nong xa » song xa, dong xa, nong va
tu nong » tu dong, tu cong, tu tong
va co » vo co

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

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