Perhaps you should try some spelling variations:
giao hanh » giao thanh, gia hanh, gian thanh
cau tren » cu tren, dau tren, ca tren
vien cac » vien bach, vien dai, vien da
sach ty » sach y, sach tu, sach thu
xang xa » lang xa, mang xa, ang xa
gia anh » gia thanh, gia dinh, gia linh
tu sach » thu sach, su sach, te sach
ve cac » va cac
vi cau » va cau, ve cau, di cau

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 ty xang xa hoi. hieu ((ve cac) OR (vien cac)) quoc ((giao hanh) or (gia anh)) vi cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty xang xa hoi. hieu ((ve cac) OR (vien cac)) quoc ((giao hanh) OR (gia anh)) vi cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty xang xa hoi. hieu ((ve cac) OR (vien cac)) quoc ((giao hanh) or (gia anh)) vi cau tren".
• Adding a wildcard symbol may retrieve word variants: tu sach ty xang xa hoi. hieu ((ve cac) OR (vien cac)) quoc ((giao hanh) or (gia anh)) vi cau tren*.