Perhaps you should try some spelling variations:
sach thuoc » sach thuong, cach thuc, hanh thuoc
thuoc dang » thuoc dung, thuoc khang, thuc dan
dang xay » dang van, van xay
hieu van » hieu va, thien van, hieu ve
van hanh » van thanh, ban hanh, van anh
tu sach » thu sach, su sach, te sach
xay hoi » xa hoi, tay hoi, cay phoi
chao tu » chao xu, cho tu, chai tu
cao tu » cao thu, co tu, cao su
vi va » vi van, vai va, vu va
thiet* » thieu*

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach thuoc dang xay hoi. ((hieu van) or (lieu va)) ((chao tu) OR (cao tu)) van hanh vi va thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach thuoc dang xay hoi. ((hieu van) OR (lieu va)) ((chao tu) OR (cao tu)) van hanh vi va thiet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach thuoc dang xay hoi. ((hieu van) or (lieu va)) ((chao tu) OR (cao tu)) van hanh vi va thiet*".