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 » dau tien, dat tren, dau tieng
ty hang » ly hang, ty xang, thi hang
van hoi » van hoa, van hoc, van hoe
duc gia » quoc gia
y hang » ly hang, yu hang, _ hang
ve cac » va cac, vien cac
do dau » doi dau, do dai, mo dau
ve cau » ke cau, va cau, le 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) OR (ty hang)) van hoi. hieu ((ve cau) or (ve cac)) duc gia thanh do dau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ((y hang) OR (ty hang)) van hoi. hieu ((ve cau) OR (ve cac)) duc gia thanh do dau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ((y hang) OR (ty hang)) van hoi. hieu ((ve cau) or (ve cac)) duc gia thanh do dau tren".
• Adding a wildcard symbol may retrieve word variants: toc sach ((y hang) OR (ty hang)) van hoi. hieu ((ve cau) or (ve cac)) duc gia thanh do dau tren*.