Perhaps you should try some spelling variations:
cam trung » cam truong, nam trung, cao trung
cac trung » cac truong, dac trung, bac trung
su triet » su viet, su tien, ve triet
cua viet » ca viet, hoa viet, cua vat
so sach » so sanh, bo sach, co sach
nang ma » tang ma, sang ma, nang cao
va hanh » van hanh, va thanh, va danh
y nang » ky nang, ly nang, v nang
ma hoi » mai hoi, xa hoi, ma hoa

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach y nang ma hoi. hieu qua ((cam trung) OR (cac trung)) va hanh vi ((su triet) or (cua viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach y nang ma hoi. hieu qua ((cam trung) OR (cac trung)) va hanh vi ((su triet) OR (cua viet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach y nang ma hoi. hieu qua ((cam trung) OR (cac trung)) va hanh vi ((su triet) or (cua viet))".
• Adding a wildcard symbol may retrieve word variants: so sach y nang ma hoi. hieu qua ((cam trung) OR (cac trung)) va hanh vi ((su triet) or (cua viet))*.