Perhaps you should try some spelling variations:
sach nuoc » sach duoc, cac nuoc, bach tuoc
hieu hien » bieu hien, dieu hien, chieu chien
su sach » so sach, vu sach
doi cua » dai cua, hoi cua
va tinh » may tinh
va dinh » van dinh, va kinh, vu dinh
sach ty » sach y, sach tu, sach thu
hieu ve » hieu va, hieu van
nang xa » nang x, lang xa, nang ma
ty nang » ky nang, ty xang, ty hang
cua tre » cua te, cuu tre, cua triet

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 ty nang xa hoi. ((hieu hien) or (hieu ve)) sach nuoc ((va dinh) OR (va tinh)) doi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty nang xa hoi. ((hieu hien) OR (hieu ve)) sach nuoc ((va dinh) OR (va tinh)) doi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ty nang xa hoi. ((hieu hien) or (hieu ve)) sach nuoc ((va dinh) OR (va tinh)) doi cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ty nang xa hoi. ((hieu hien) or (hieu ve)) sach nuoc ((va dinh) OR (va tinh)) doi cua tre*.