Perhaps you should try some spelling variations:
doc sach » hoc sach, toc sach, nuoc sach
dinh va » dinh van, dinh ve, tinh va
va dinh » van dinh, va kinh, va tinh
ve cham » va cham, ve chat, vu cham
cua tre » cua te, cuu tre, cua triet
ty hang » ly hang, ty xang, thi hang
ty nang » ky nang, ty xang, ly nang
luc va » duc va, tuc va, loc va
va cua » va chua, via cua, ca cua
ve cam » ve cac, va cam, ve cai

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 ((ty nang) or (ty hang)) xa hoi. hieu ((ve cam) or (ve cham)) luc va dinh va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach ((ty nang) OR (ty hang)) xa hoi. hieu ((ve cam) OR (ve cham)) luc va dinh va cua tre.
• Adding a wildcard symbol may retrieve word variants: doc sach ((ty nang) or (ty hang)) xa hoi. hieu ((ve cam) or (ve cham)) luc va dinh va cua tre*.