Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
ban benh » san benh, ba benh, ban banh
quoc ban » quoc bao, quoc lan, quoc quan
mai hoi » mai khoi, dai hoi, lai hoi
van cao » van bao, van hao, van cau
benh vi » benh va, benh ve, benh li
te sach » toc sach
y nang » ky nang, ly nang, v nang
ma hoi » xa hoi, ma hoa, me 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: te sach y nang ((ma hoi) OR (mai hoi)). hieu ((van cao) or (van dao)) quoc ban benh vi su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach y nang ((ma hoi) OR (mai hoi)). hieu ((van cao) OR (van dao)) quoc ban benh vi su triet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach y nang ((ma hoi) OR (mai hoi)). hieu ((van cao) or (van dao)) quoc ban benh vi su triet*".