Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
su sach » so sach, vu sach
va hanh » van hanh, va thanh, va danh
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va
nang xa » nang x, lang xa, nang ma
cua tre » cua te, cuu tre, cua triet
cam lo » nam lo, cam ly, cam o
vi cua » vai cua, di 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 loc) or (cam lo)) va hanh vi 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 loc) OR (cam lo)) va hanh vi 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 loc) or (cam lo)) va hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ky nang xa hoi. ((hieu ve) OR (hieu van)) ((cam loc) or (cam lo)) va hanh vi cua tre*.