Perhaps you should try some spelling variations:
su triet » su viet, ve triet
van hanh » van thanh, ban hanh, van anh
hieu van » hieu va, thien van, lieu va
su sach » so sach, vu sach
xuc van » duc van, luc van, vuc van
van dau » van dao, phan dau
dau xuc » dau xac, dau xua, dau nuoc
sach ky » sac ky, sach y, sach ty
van hoc » van hoa
ky dang » ky nang, ky danh
su tien » su kien, su hien, tu tieng

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 ky dang ((van loi) or (van hoc)). hieu van dau xuc van hanh vi ((su triet) OR (su tien))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky dang ((van loi) OR (van hoc)). hieu van dau xuc van hanh vi ((su triet) OR (su tien)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky dang ((van loi) or (van hoc)). hieu van dau xuc van hanh vi ((su triet) OR (su tien))".
• Adding a wildcard symbol may retrieve word variants: su sach ky dang ((van loi) or (van hoc)). hieu van dau xuc van hanh vi ((su triet) OR (su tien))*.