Perhaps you should try some spelling variations:
su sach » so sach, vu sach
sach ty » sach y, sach tu, sach thu
ty tang » tay tang, ty xang, ty hang
hieu ve » hieu va, hieu van
cac luc » cau luc, coc luc, cac nuoc
va danh » va dinh, va dan, va hanh
danh ki » danh di, danh kien, danh gia
su viet » so viet
ve cac » va cac, vien cac
luc va » duc va, tuc va, loc va
ki su » ky 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 ty tang ((xa hoi) or (ma hoa)). hieu ve cac luc va danh ki su viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty tang ((xa hoi) OR (ma hoa)). hieu ve cac luc va danh ki su viet.
• Adding a wildcard symbol may retrieve word variants: su sach ty tang ((xa hoi) or (ma hoa)). hieu ve cac luc va danh ki su viet*.