Perhaps you should try some spelling variations:
toc sach » hoc sach, thuoc sach, nuoc sach
dinh cuu » dinh chi
doc sach » hoc sach, nuoc sach, dac sac
thu nong » thu cong, tu nong, phu nong
chat tu » nhat tu, chai tu, chay tu
va hang » van hang, va nang, va lang
hieu va » lieu va, hieu qua
va chat » van chat, va phat, cao chat
nong xa » song xa, dong xa, nong va
di cuu » di cau, di cua

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)) thu nong xa hoi. hieu va chat tu va hang ((di cuu) or (dinh cuu)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (doc sach)) thu nong xa hoi. hieu va chat tu va hang ((di cuu) OR (dinh cuu)) tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) OR (doc sach)) thu nong xa hoi. hieu va chat tu va hang ((di cuu) or (dinh cuu)) tre*".