Perhaps you should try some spelling variations:
viet sach » viet anh, dien sach, viet tech
lieu viet » sieu viet, lieu vien, tieu viet
sach nuoc » sach duoc, cac nuoc, bach tuoc
tinh doi » trinh doc, trinh do, tinh hoc
xanh doi » xanh di, thanh doi, anh doc
dau tren » dau tien, dat tren, dau tieng
xang xa » lang xa, mang xa, ang xa
su sach » so sach
vu sach » vu bach, vu khach

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((vu sach) OR (su sach)) ty xang xa hoi. lieu viet sach nuoc va ((xanh doi) or (tinh doi)) dau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((vu sach) OR (su sach)) ty xang xa hoi. lieu viet sach nuoc va ((xanh doi) OR (tinh doi)) dau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((vu sach) OR (su sach)) ty xang xa hoi. lieu viet sach nuoc va ((xanh doi) or (tinh doi)) dau tren".
• Adding a wildcard symbol may retrieve word variants: ((vu sach) OR (su sach)) ty xang xa hoi. lieu viet sach nuoc va ((xanh doi) or (tinh doi)) dau tren*.