Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
quoc ban » quoc bao, quoc quan, quoc binh
quoc lan » nuoc luan, quoc quan, quoc danh
sach tu » sach thu, cach tu, sach uu
sach ty » sach y, sach thu, xach tay
nang xa » nang x, lang xa, nang ma
cua tre » cua te, cuu tre, cua triet
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: tu ((sach tu) or (sach ty)) nang xa hoi. hieu van nam ((quoc ban) OR (quoc lan)) hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach tu) OR (sach ty)) nang xa hoi. hieu van nam ((quoc ban) OR (quoc lan)) hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach tu) or (sach ty)) nang xa hoi. hieu van nam ((quoc ban) OR (quoc lan)) hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: tu ((sach tu) or (sach ty)) nang xa hoi. hieu van nam ((quoc ban) OR (quoc lan)) hanh vi cua tre*.