Perhaps you should try some spelling variations:
thanh vi » hanh vi, thanh va, thanh ve
va thanh » gia thanh, ban thanh, va tinh
vien cac » vien bach, vien dai, vien da
so sach » so sanh, bo sach, co sach
sach ty » sach y, sach tu, sach thu
truc va » thuc va, thuc vat, trung va
su tien » su kien, su hien, tu tieng
ve cac » va cac
o hoi » co hoi, o hoc, o hai
x hoi » xa hoi, x ho, 5 hoi
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: so sach ty xang ((x hoi) or (o hoi)). hieu ((ve cac) OR (vien cac)) truc va thanh vi su tien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ty xang ((x hoi) OR (o hoi)). hieu ((ve cac) OR (vien cac)) truc va thanh vi su tien.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ty xang ((x hoi) or (o hoi)). hieu ((ve cac) OR (vien cac)) truc va thanh vi su tien".
• Adding a wildcard symbol may retrieve word variants: so sach ty xang ((x hoi) or (o hoi)). hieu ((ve cac) OR (vien cac)) truc va thanh vi su tien*.