Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hanh dai » hanh tai, hanh dao, vanh dai
tu nong » tu dong, tu cong, tu tong
nong va » nong van, dong va, cong va
hieu va » lieu va, hieu qua
xa hanh » xa thanh, xa khanh, va hanh
cua tre » cua te, cuu tre, cua triet
va hoi » xa hoi, va hoc, va hoa
co duc » co duoc, cao duc, do duc
duc xa » duoc xa, tuc xa, duc va
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: ((te sach) or (toc sach)) tu nong va hoi. hieu va co duc xa hanh dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) tu nong va hoi. hieu va co duc xa hanh dai cua tre.
• Adding a wildcard symbol may retrieve word variants: ((te sach) or (toc sach)) tu nong va hoi. hieu va co duc xa hanh dai cua tre*.