Perhaps you should try some spelling variations:
so sach » so sanh, bo sach, co sach
tinh va » tich va, trinh van, trinh vat
va tinh » may tinh
coc tuc » coc luc, hoc thuc, doc thuc
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu van
ky dang » ky nang, ky danh
ky lang » ky nang, ky tang, tay lang
tuc va » thuc va, truc va, tuc xa
va cua » va chua, via cua, ca cua

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: so sach ((ky lang) OR (ky dang)) xa hoi. ((hieu ve) or (hieu va)) coc tuc va tinh va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ((ky lang) OR (ky dang)) xa hoi. ((hieu ve) OR (hieu va)) coc tuc va tinh va cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ((ky lang) OR (ky dang)) xa hoi. ((hieu ve) or (hieu va)) coc tuc va tinh va cua tre".
• Adding a wildcard symbol may retrieve word variants: so sach ((ky lang) OR (ky dang)) xa hoi. ((hieu ve) or (hieu va)) coc tuc va tinh va cua tre*.