Perhaps you should try some spelling variations:
quoc ban » quoc bao, quoc lan, quoc quan
sach tu » sach thu, cach tu, sach uu
sach ty » sach y, sach thu, xach tay
cong xa » cong xay, cong xua, cong ha
hieu va » lieu va, hieu qua
duc van » duc va, duc tan, duc manh
cuu tre » cua tre, cau tren, cau treo
va cam » va cham, va cac, va cao
vi cuu » vi luu, vinh cuu

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)) cong xa hoi. hieu va cam ((duc van) or (quoc ban)) hanh vi cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach tu) OR (sach ty)) cong xa hoi. hieu va cam ((duc van) OR (quoc ban)) hanh vi cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach tu) OR (sach ty)) cong xa hoi. hieu va cam ((duc van) or (quoc ban)) hanh vi cuu tre".
• Adding a wildcard symbol may retrieve word variants: tu ((sach tu) OR (sach ty)) cong xa hoi. hieu va cam ((duc van) or (quoc ban)) hanh vi cuu tre*.