Perhaps you should try some spelling variations:
lam quoc » lam duoc, nam quoc, lam thuoc
quoc ban » quoc bao, quoc lan, quoc quan
hieu van » hieu va, thien van, lieu va
benh vi » benh va, benh ve, benh li
banh vi » hanh vi, ban vi, banh chi
su sach » so sach, vu sach
van lam » van nam
ky dang » ky nang, ky danh
ky lang » ky nang, ky tang, tay lang
cua tre » cua te, cuu tre, cua triet

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 lang) or (ky dang)) xa hoi. hieu van lam quoc ban ((banh vi) OR (benh vi)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ((ky lang) OR (ky dang)) xa hoi. hieu van lam quoc ban ((banh vi) OR (benh vi)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ((ky lang) or (ky dang)) xa hoi. hieu van lam quoc ban ((banh vi) OR (benh vi)) cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ((ky lang) or (ky dang)) xa hoi. hieu van lam quoc ban ((banh vi) OR (benh vi)) cua tre*.