Perhaps you should try some spelling variations:
sang ma » tang ma, nang ma, sang tao
va hanh » van hanh, va thanh, va danh
cam duc » cam xuc, cao duc, nam duoc
hieu ve » hieu va, hieu van
tu cach » tu cac
ky sang » ky nang, ky dang, ky tang
su sach » so sach, vu sach
cua tre » cua te, cuu tre, cua triet
ma hoi » mai hoi, xa hoi, ma hoa
vi cua » vai cua, di cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu cach) or (su sach)) ky sang ma hoi. hieu ve ((cam duc) OR (pham duc)) va hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu cach) OR (su sach)) ky sang ma hoi. hieu ve ((cam duc) OR (pham duc)) va hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu cach) or (su sach)) ky sang ma hoi. hieu ve ((cam duc) OR (pham duc)) va hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((tu cach) or (su sach)) ky sang ma hoi. hieu ve ((cam duc) OR (pham duc)) va hanh vi cua tre*.