Perhaps you should try some spelling variations:
sach nang » cach mang, sach dung, sach danh
nang mang » nang sang, nang hang, nhanh mang
ban hanh » ban hang
vu sach » vu bach, su sach, vu khach
may hoi » may thoi, tay hoi, mai hoi
hieu va » lieu va, hieu qua
cac luc » cau luc, coc luc, cac nuoc
va hanh » van hanh, va thanh, va danh
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: vu sach nang mang may hoi. hieu va cac luc ((va hanh) or (ban hanh)) vi va thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach nang mang may hoi. hieu va cac luc ((va hanh) OR (ban hanh)) vi va thiet.
• Adding a wildcard symbol may retrieve word variants: vu sach nang mang may hoi. hieu va cac luc ((va hanh) or (ban hanh)) vi va thiet*.