Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
thu sach » tu sach, thuat sach, thu hoach
toan tai » toan tap, doanh tai, toan ban
cau theo » cau thi, cau tao
xang xa » lang xa, mang xa, ang xa
hieu va » lieu va, hieu qua
cao duc » dao duc, cao suc, giao duc
han tai » hang tai, nhan tai, van tai
va cao » va cac, va co, va dao

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((thu sach) OR (thuoc sach)) ty xang xa hoi. hieu va cao duc va ((han tai) or (toan tai)) cau theo~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thu sach) OR (thuoc sach)) ty xang xa hoi. hieu va cao duc va ((han tai) OR (toan tai)) cau theo.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((thu sach) OR (thuoc sach)) ty xang xa hoi. hieu va cao duc va ((han tai) or (toan tai)) cau theo".
• Adding a wildcard symbol may retrieve word variants: ((thu sach) OR (thuoc sach)) ty xang xa hoi. hieu va cao duc va ((han tai) or (toan tai)) cau theo*.