Perhaps you should try some spelling variations:
nuoc sach » nguoi sach, hoc sach, cuoc cach
hieu cua » hieu qua, dieu cua, bieu cua
dieu tra » dieu tri, kiem tra, dieu cua
va thanh » gia thanh, ban thanh, le thanh
sach ty » sach y, sach tu, sach thu
xang xa » lang xa, mang xa, ang xa
va tinh » may tinh
ca viet » va viet, co viet, hoa viet
cac ly » cac ky, cac le, cam ly
tai ca » tai cac, tai cao, tai cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: nuoc sach ty xang xa hoi. ((hieu cua) or (dieu tra)) cac ly ((va thanh) OR (va tinh)) tai ca viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: nuoc sach ty xang xa hoi. ((hieu cua) OR (dieu tra)) cac ly ((va thanh) OR (va tinh)) tai ca viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "nuoc sach ty xang xa hoi. ((hieu cua) or (dieu tra)) cac ly ((va thanh) OR (va tinh)) tai ca viet".
• Adding a wildcard symbol may retrieve word variants: nuoc sach ty xang xa hoi. ((hieu cua) or (dieu tra)) cac ly ((va thanh) OR (va tinh)) tai ca viet*.