Perhaps you should try some spelling variations:
vay sach » tay sach, van sach, vay khach
hanh vai » hanh vi, hanh va, hanh tai
van hanh » van thanh, ban hanh, van anh
va triet » va trien, ve triet, cua triet
sach ty » sach y, sach tu, sach thu
ve cham » va cham, ve chat, vu cham
tang ma » mang may, tang van
ty tang » tay tang, ty xang, ty hang
ma hoi » mai hoi, xa hoi, ma hoa
ve cam » ve cac, va cam, ve cai
lo van » le van, vo van, so van
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: vay sach ty tang ma hoi. hieu ((ve cam) or (ve cham)) lo van hanh vai ((va triet) OR (va thiet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vay sach ty tang ma hoi. hieu ((ve cam) OR (ve cham)) lo van hanh vai ((va triet) OR (va thiet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "vay sach ty tang ma hoi. hieu ((ve cam) or (ve cham)) lo van hanh vai ((va triet) OR (va thiet))".
• Adding a wildcard symbol may retrieve word variants: vay sach ty tang ma hoi. hieu ((ve cam) or (ve cham)) lo van hanh vai ((va triet) OR (va thiet))*.