Perhaps you should try some spelling variations:
thu sach » thuat sach, thuoc sach, thu hoach
hieu van » hieu va, thien van, lieu va
thanh de » hanh de, thanh ve, thanh do
cua viet » ca viet, hoa viet, cua vat
tu sach » su sach, te sach, tu cach
hang xa » hoang xa, hang va, hang ca
cac luc » cau luc, cac nuoc, cac cuoc
y hang » ly hang, ty hang, yu hang
de cua » le cua, te cua, dieu cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu sach) OR (thu sach)) y hang xa hoi. hieu van ((cac luc) or (coc luc)) gia thanh de cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thu sach)) y hang xa hoi. hieu van ((cac luc) OR (coc luc)) gia thanh de cua viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) OR (thu sach)) y hang xa hoi. hieu van ((cac luc) or (coc luc)) gia thanh de cua viet".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) OR (thu sach)) y hang xa hoi. hieu van ((cac luc) or (coc luc)) gia thanh de cua viet*.