Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
van hanh » van thanh, ban hanh, van anh
hieu va » lieu va, hieu qua
cac xuc » cam xuc, cac nuoc, chat xuc
va hanh » va thanh, va danh, ban hanh
dai cuu » dai cua, dai huu
cuu tre » cua tre, cau tren, cau treo
xang o » lang o, dang o
tang o » trang o, lang o

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 y ((xang o) OR (tang o)) hoc. hieu va cac xuc ((va hanh) or (van hanh)) dai cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach y ((xang o) OR (tang o)) hoc. hieu va cac xuc ((va hanh) OR (van hanh)) dai cuu tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach y ((xang o) OR (tang o)) hoc. hieu va cac xuc ((va hanh) or (van hanh)) dai cuu tre*".