Perhaps you should try some spelling variations:
doc sach » hoc sach, toc sach, nuoc sach
van hanh » van thanh, ban hanh, van anh
tang van » dang van, hoang van, trong van
soc van » hoc van, oc van, sac van
va cham » va chat, va tham
sach ky » sac ky, sach y, sach ty
hieu va » lieu va, hieu qua
mang xa » lang xa, mang may, dang xay

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc sach ky ((mang xa) or (tang van)) hoi. hieu va cham soc van hanh ((vi luu) OR (vi lua)) tru~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach ky ((mang xa) OR (tang van)) hoi. hieu va cham soc van hanh ((vi luu) OR (vi lua)) tru*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc sach ky ((mang xa) or (tang van)) hoi. hieu va cham soc van hanh ((vi luu) OR (vi lua)) tru*".