Perhaps you should try some spelling variations:
cam truc » cau truc, lam truoc, nam truoc
van nang » van quang, van dong, van dung
van hanh » van thanh, ban hanh, van anh
nam truc » nam truoc, nam thuc, nam trung
hanh di » hanh vi, hanh de, hang di
su sach » so sach, vu sach
hieu ve » hieu va, hieu van
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: su sach ((van nang) or (van ban)) xa hoi. hieu ve ((cam truc) OR (nam truc)) van hanh di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ((van nang) OR (van ban)) xa hoi. hieu ve ((cam truc) OR (nam truc)) van hanh di cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ((van nang) or (van ban)) xa hoi. hieu ve ((cam truc) OR (nam truc)) van hanh di cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ((van nang) or (van ban)) xa hoi. hieu ve ((cam truc) OR (nam truc)) van hanh di cua tre*.