Perhaps you should try some spelling variations:
thien van » thi van
hoc sach » hoc sinh, hoc cac, hoc anh
cam thuc » am thuc, cam thu, can thuc
nam thuc » nam thuoc, am thuc, nam thu
te sach » toc sach
va hanh » van hanh, va thanh, va danh
cua tre » cua te, cuu tre, cua triet
vi cua » vai cua, di cua
x hoi » xa hoi, o hoi, x ho

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((te sach) or (hoc sach)) ky nang x hoi. thien van ((cam thuc) OR (nam thuc)) va hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (hoc sach)) ky nang x hoi. thien van ((cam thuc) OR (nam thuc)) va hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) or (hoc sach)) ky nang x hoi. thien van ((cam thuc) OR (nam thuc)) va hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((te sach) or (hoc sach)) ky nang x hoi. thien van ((cam thuc) OR (nam thuc)) va hanh vi cua tre*.