Perhaps you should try some spelling variations:
tu tieng » luc tieng, tu tuong, tu trong
su triet » su viet, su tien, ve triet
van hanh » van thanh, ban hanh, van anh
duc van » duc va, duc tan, duc manh
cam duc » cam xuc, cao duc, pham duc
tu sach » thu sach, su sach, te sach
hieu ve » hieu va, hieu van
sach v » sach va, sach y, sach 2
v nang » va nang, vu nang, van nang
ve cam » ve cham, ve cac, va cam
o hoi » co hoi, o hoc, o hai
x hoi » xa hoi, x ho, 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: tu sach v nang ((x hoi) OR (o hoi)). hieu ve cam duc van hanh vi ((su triet) or (tu tieng))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach v nang ((x hoi) OR (o hoi)). hieu ve cam duc van hanh vi ((su triet) OR (tu tieng))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach v nang ((x hoi) OR (o hoi)). hieu ve cam duc van hanh vi ((su triet) or (tu tieng))*".