Perhaps you should try some spelling variations:
doc sach » hoc sach, toc sach, nuoc sach
hanh di » hanh vi, hanh de, hang di
va hanh » van hanh, va thanh, va danh
cua tre » cua te, cuu tre, cua triet
va cam » va cham, va cac, va cai
y nang » ky nang, ly nang, may nang
va cao » va cac, va co, va dao
v nang » va nang, vu nang, van nang
xuc va » duc va, tuc va, luc va
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: doc sach ((y nang) or (v nang)) xa hoi. hieu ((va cam) OR (va cao)) xuc va hanh di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach ((y nang) OR (v nang)) xa hoi. hieu ((va cam) OR (va cao)) xuc va hanh di cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc sach ((y nang) or (v nang)) xa hoi. hieu ((va cam) OR (va cao)) xuc va hanh di cua tre".
• Adding a wildcard symbol may retrieve word variants: doc sach ((y nang) or (v nang)) xa hoi. hieu ((va cam) OR (va cao)) xuc va hanh di cua tre*.