Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
van hanh » van thanh, ban hanh, van anh
sach ty » sach y, sach tu, sach thu
dai cuu » dai cua, dai huu
va danh » va dinh, va dan, dia danh
va hanh » va thanh, ban hanh, dao hanh
cac xuc » cam xuc, cac nuoc, chat xuc
hieu va » lieu va, hieu qua
cuu tre » cua tre, cau tren, cau treo
xang o » lang o, tang o, dang o
o hoc » co hoc, mo hoc, so hoc

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