Perhaps you should try some spelling variations:
thanh dat » thanh san, thanh hai, thanh van
va thanh » gia thanh, ban thanh, va tinh
may thoi » gay thoi, may thi, tay thoi
su sach » so sach, vu sach
cac tac » cac toc, cac bac, cac dac
sach ky » sac ky, sach y, sach ty
cac tuc » cac toc, cac tu, cac nuoc
may hoi » tay hoi, mai hoi, may hmi
hieu va » lieu va, hieu qua
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) OR (cac tac)) va thanh 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) OR (cac tac)) va thanh 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) OR (cac tac)) va thanh dat su viet".
• Adding a wildcard symbol may retrieve word variants: su sach ky mang ((may hoi) or (may thoi)). hieu va ((cac tuc) OR (cac tac)) va thanh dat su viet*.