Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
van chat » cao chat
toc sach » hoc sach, doc sach, thuoc sach
chat hoc » chat hoa, chat thom, cho hoc
cua tre » cuu tre, cua triet, dua tren
hanh va » hang va, hanh vi
va hanh » van hanh, va thanh, va danh
tu cach » tu cac
nang ma » tang ma, sang ma, nang cao
ma hoi » mai hoi, xa hoi, ma hoa
cua te » cua tu

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 (toc sach)) ky nang ma hoi. hieu van chat hoc va hanh va ((cua tre) OR (cua te))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu cach) OR (toc sach)) ky nang ma hoi. hieu van chat hoc va hanh va ((cua tre) OR (cua te)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu cach) or (toc sach)) ky nang ma hoi. hieu van chat hoc va hanh va ((cua tre) OR (cua te))".
• Adding a wildcard symbol may retrieve word variants: ((tu cach) or (toc sach)) ky nang ma hoi. hieu van chat hoc va hanh va ((cua tre) OR (cua te))*.