Perhaps you should try some spelling variations:
dau tren » dau tien, dat tren, dau tieng
van hanh » van thanh, ban hanh, van anh
vien dai » hien dai
sach ty » sach y, sach tu, sach thu
va hanh » va thanh, va danh, ban hanh
xang xa » lang xa, mang xa, ang xa
lai dau » lam dau, lan dau, lai chau
te sach » toc sach
ve cam » ve cham, ve cac, va cam

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sach ty xang xa hoi. hieu ((ve cam) or (vien dai)) trung ((va hanh) OR (van hanh)) lai dau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ty xang xa hoi. hieu ((ve cam) OR (vien dai)) trung ((va hanh) OR (van hanh)) lai dau tren*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ty xang xa hoi. hieu ((ve cam) or (vien dai)) trung ((va hanh) OR (van hanh)) lai dau tren*".