Perhaps you should try some spelling variations:
van thiet » va thiet, dan thiet, can thiet
va thanh » gia thanh, ban thanh, va tinh
van giao » nang giao, toan giao, dan gian
hieu van » hieu va, thien van, lieu va
sach lo » sach dao, sach doi, sach hoi
va hanh » van hanh, va danh, ban hanh
xang xa » lang xa, mang xa, dang xay
hai van » thai van, ha van, hai tan
su sach » so sach, vu sach
ang xa » lang xa, mang xa, dang xay

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach lo ((xang xa) OR (ang xa)) hoi. hieu van giao duc ((va hanh) or (va thanh)) hai van thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach lo ((xang xa) OR (ang xa)) hoi. hieu van giao duc ((va hanh) OR (va thanh)) hai van thiet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach lo ((xang xa) OR (ang xa)) hoi. hieu van giao duc ((va hanh) or (va thanh)) hai van thiet".
• Adding a wildcard symbol may retrieve word variants: su sach lo ((xang xa) OR (ang xa)) hoi. hieu van giao duc ((va hanh) or (va thanh)) hai van thiet*.