Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
van chat » cao chat
ban hanh » ban hang
ky hang » ky nang, ly hang, ty hang
ky dang » ky nang, ky danh
hoa hoi » khoa hoi, hoa hoc, hoa doi
van cau » van dau, van hau, toan cau
cua tre » cua te, cuu tre, cua triet
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: toc sach ((ky hang) or (ky dang)) hoa hoi. thien ((van cau) OR (van chat)) cua ban hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ((ky hang) OR (ky dang)) hoa hoi. thien ((van cau) OR (van chat)) cua ban hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ((ky hang) or (ky dang)) hoa hoi. thien ((van cau) OR (van chat)) cua ban hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: toc sach ((ky hang) or (ky dang)) hoa hoi. thien ((van cau) OR (van chat)) cua ban hanh vi cua tre*.