Perhaps you should try some spelling variations:
va thanh » gia thanh, ban thanh, le thanh
may thoi » gay thoi, may thi, tay thoi
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
va tinh » may tinh
cac tuc » cac toc, cac tu, cac tac
hieu va » lieu va, hieu qua
may hoi » tay hoi, mai hoi, may hmi
ky mang » ky nang, ke mang, ky dang
su viet » so viet
dat su » sat su

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 ky mang ((may hoi) or (may thoi)). hieu va cac tuc ((va thanh) OR (va tinh)) dat su viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky mang ((may hoi) OR (may thoi)). hieu va cac tuc ((va thanh) OR (va tinh)) dat su viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky mang ((may hoi) or (may thoi)). hieu va cac tuc ((va thanh) OR (va tinh)) dat su viet".
• Adding a wildcard symbol may retrieve word variants: su sach ky mang ((may hoi) or (may thoi)). hieu va cac tuc ((va thanh) OR (va tinh)) dat su viet*.