Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
van hanh » van thanh, ban hanh, van anh
hanh di » hanh vi, hanh de, hang di
day mua » day cua, dan mua
nay mua » nam mua, nay lua
ky dang » ky nang, ky danh
ky tang » ky nang, kho tang, ky trong
cua tre » cua te, cuu tre, cua triet
di cua » dai cua, doi cua, de 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 tang) or (ky dang)) xa hoi. lieu va ((nay mua) or (day mua)) van hanh di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ((ky tang) OR (ky dang)) xa hoi. lieu va ((nay mua) OR (day mua)) van hanh di cua tre.
• Adding a wildcard symbol may retrieve word variants: toc sach ((ky tang) or (ky dang)) xa hoi. lieu va ((nay mua) or (day mua)) van hanh di cua tre*.