Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
cua tre » cua te, cuu tre, cua triet
va hanh » van hanh, va thanh, va danh
ve chat » va chat, van chat
ve cham » va cham, vu cham, ve chim
nang ma » tang ma, sang ma, nang cao
ma hoi » mai hoi, xa hoi, ma hoa
tuc va » thuc va, truc va, tuc xa
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: ((vu bach) or (toc sach)) ky nang ma hoi. hieu ((ve cham) OR (ve chat)) tuc va hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((vu bach) OR (toc sach)) ky nang ma hoi. hieu ((ve cham) OR (ve chat)) tuc va hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((vu bach) or (toc sach)) ky nang ma hoi. hieu ((ve cham) OR (ve chat)) tuc va hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((vu bach) or (toc sach)) ky nang ma hoi. hieu ((ve cham) OR (ve chat)) tuc va hanh vi cua tre*.