Perhaps you should try some spelling variations:
cac thuc » cach thuc, cac thu, can thuc
thanh vi » hanh vi, thanh ve, nhanh vi
thanh va » thanh van, hanh va, thanh ha
su triet » su viet, su tien, ve triet
su sach » so sach, vu sach
sach ty » sach y, sach tu, sach thu
hieu ve » hieu va, hieu van
ve cac » va cac, vien cac
x hoi » xa hoi, o hoi, 5 hoi

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 xang ((x hoi) or (x ho)). hieu ve cac thuc vat ((thanh vi) OR (thanh va)) su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty xang ((x hoi) OR (x ho)). hieu ve cac thuc vat ((thanh vi) OR (thanh va)) su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ty xang ((x hoi) or (x ho)). hieu ve cac thuc vat ((thanh vi) OR (thanh va)) su triet".
• Adding a wildcard symbol may retrieve word variants: su sach ty xang ((x hoi) or (x ho)). hieu ve cac thuc vat ((thanh vi) OR (thanh va)) su triet*.