Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
van hanh » van thanh, ban hanh, van ban
sach ky » sac ky, sach y, sach ty
ky dang » ky nang, ky danh
dang ma » dang mau, dang mam, dang mat
hieu va » hieu qua
van anh » van thanh, tuan anh, van minh
cua tre » cua te, cuu tre, cua triet

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 dang ma hoa. ((hieu va) or (lieu va)) cam xuc ((van hanh) OR (van anh)) dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky dang ma hoa. ((hieu va) OR (lieu va)) cam xuc ((van hanh) OR (van anh)) dai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ky dang ma hoa. ((hieu va) or (lieu va)) cam xuc ((van hanh) OR (van anh)) dai cua tre".
• Adding a wildcard symbol may retrieve word variants: toc sach ky dang ma hoa. ((hieu va) or (lieu va)) cam xuc ((van hanh) OR (van anh)) dai cua tre*.