Perhaps you should try some spelling variations:
su triet » su viet, ve triet
thanh vi » hanh vi, thanh va, thanh ve
ha thanh » va thanh, pham thanh, phan thanh
vu sach » vu bach, su sach, vu khach
sach ky » sac ky, sach y, sach ty
cac tac » cac toc, cac bac, cac dac
su tien » su kien, su hien, tu tieng
hieu ve » hieu va, hieu van
tac ha » bac ha, tac da, tac xa
ve cac » va cac, vien cac
o hoc » co hoc, mo hoc, so hoc
o hoi » co hoi, o hai, o hoa

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu sach ky nang ((o hoi) OR (o hoc)). hieu ve cac tac ha thanh vi ((su triet) or (su tien))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach ky nang ((o hoi) OR (o hoc)). hieu ve cac tac ha thanh vi ((su triet) OR (su tien)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu sach ky nang ((o hoi) OR (o hoc)). hieu ve cac tac ha thanh vi ((su triet) or (su tien))".
• Adding a wildcard symbol may retrieve word variants: vu sach ky nang ((o hoi) OR (o hoc)). hieu ve cac tac ha thanh vi ((su triet) or (su tien))*.