Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
doc sach » hoc sach, toc sach, nuoc sach
thanh mo » thanh moi, thanh mot, thanh do
dau tren » dau tien, dat tren, dau tieng
hieu ve » hieu va, hieu van
cau duc » cau luc, chu duc, cau truc
cao duc » dao duc, cao suc, giao duc
y hang » ly hang, ty hang, yu hang
va hoi » xa hoi, va hoc, va hoa

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((doc sach) or (thuoc sach)) y hang va hoi. hieu ve ((cau duc) or (cao duc)) gia thanh mo dau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((doc sach) OR (thuoc sach)) y hang va hoi. hieu ve ((cau duc) OR (cao duc)) gia thanh mo dau tren.
• Adding a wildcard symbol may retrieve word variants: ((doc sach) or (thuoc sach)) y hang va hoi. hieu ve ((cau duc) or (cao duc)) gia thanh mo dau tren*.