Perhaps you should try some spelling variations:
su sach » so sach, vu sach
va hanh » van hanh, va thanh, va danh
sach tu » sach thu, cach tu, sach ty
su viet » so viet
tu tang » tuc tang, tu trang, tu tong
ma hoi » mai hoi, xa hoi, me hoi
ke cau » ket cau
tuc va » thuc va, truc va, tuc xa
ve cau » va cau, ve cac, le cau
vi su » va su, ve su, ki su

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach tu tang ((ma hoi) or (ma hoa)). hieu ((ve cau) or (ke cau)) tuc va hanh vi su viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach tu tang ((ma hoi) OR (ma hoa)). hieu ((ve cau) OR (ke cau)) tuc va hanh vi su viet.
• Adding a wildcard symbol may retrieve word variants: su sach tu tang ((ma hoi) or (ma hoa)). hieu ((ve cau) or (ke cau)) tuc va hanh vi su viet*.