Perhaps you should try some spelling variations:
va thieu » va thiet, va hieu, va tieu
sach ty » sach y, sach tu, sach thu
han tai » hang tai, nhan tai, van tai
thuc va » thuc vat, thuc dan, thuc day
va cham » va chat, va tham
vu cham » vu kham, tu cham, qua cham
va han » va phan, van han, va hanh
tai va » thai va, mai va, tri va
x hoi » xa hoi, o hoi, x ho

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) or (sach thieu)) nang x hoi. hieu ((vu cham) or (va cham)) thuc va han tai va thieu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ty) OR (sach thieu)) nang x hoi. hieu ((vu cham) OR (va cham)) thuc va han tai va thieu.
• Adding a wildcard symbol may retrieve word variants: su ((sach ty) or (sach thieu)) nang x hoi. hieu ((vu cham) or (va cham)) thuc va han tai va thieu*.