Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
thanh do » thanh de, thanh pho, thanh hoa
dau tren » dat tren, dau tieng, dau trong
dau tien » van tien
van hoi » van hoc, van hoe, van loi
hieu ke » hieu kem, chieu ke, hieu ky
cau duc » cao duc, cau luc, chu duc
duc gia » quoc gia
y hang » ly hang, ty hang, yu hang
ke cau » ket cau

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach y hang ((van hoi) OR (van hoa)). hieu ke cau duc gia thanh do ((dau tren) or (dau tien))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach y hang ((van hoi) OR (van hoa)). hieu ke cau duc gia thanh do ((dau tren) OR (dau tien)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach y hang ((van hoi) OR (van hoa)). hieu ke cau duc gia thanh do ((dau tren) or (dau tien))".
• Adding a wildcard symbol may retrieve word variants: toc sach y hang ((van hoi) OR (van hoa)). hieu ke cau duc gia thanh do ((dau tren) or (dau tien))*.