Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
trinh ve » trinh he, trinh va, trinh vi
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, nang ma
hieu ve » hieu va
cua tre » cua te, cuu tre, cua triet
xuc va » tuc va, luc va, xac va
ve cua » le cua, de cua, te cua

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 nang xa hoi. ((hieu ve) or (hieu van)) cam ((xuc va) OR (duc va)) trinh ve cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky nang xa hoi. ((hieu ve) OR (hieu van)) cam ((xuc va) OR (duc va)) trinh ve cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky nang xa hoi. ((hieu ve) or (hieu van)) cam ((xuc va) OR (duc va)) trinh ve cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ky nang xa hoi. ((hieu ve) or (hieu van)) cam ((xuc va) OR (duc va)) trinh ve cua tre*.