Perhaps you should try some spelling variations:
thanh doi » thanh loi, thanh moi, thanh do
thu sach » tu sach, thuat sach, thuoc sach
hieu van » hieu va, thien van, lieu va
van pham » san pham, van phan, van phat
thanh di » thanh de, thanh do, thanh dinh
cau tren » cu tren, dau tren, ca tren
cua viet » ca viet, hoa viet, cua vat
sach ky » sac ky, sach y, sach ty

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 ky nang x ho. hieu van pham duc va ((thanh di) OR (thanh doi)) ((cau tren) or (cua viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky nang x ho. hieu van pham duc va ((thanh di) OR (thanh doi)) ((cau tren) OR (cua viet))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ky nang x ho. hieu van pham duc va ((thanh di) OR (thanh doi)) ((cau tren) or (cua viet))*".