Perhaps you should try some spelling variations:
dinh viet » ninh viet, danh viet, trinh viet
dinh vien » sinh vien, dinh dien, dinh kien
thu sach » tu sach, thuat sach, thuoc sach
dang van » hoang van, hang va
sach ky » sac ky, sach y, sach ty
ca truc » cau truc, ca tru, ba truc
truc va » thuc va, thuc vat, trung va
lang xa » lang ha, dang xay, lang van
qua ca » qua cac, qua cua, qua cai

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach ky ((lang xa) or (dang van)) hoi. hieu qua ca truc va ((dinh vien) OR (dinh viet)) cac tro~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky ((lang xa) OR (dang van)) hoi. hieu qua ca truc va ((dinh vien) OR (dinh viet)) cac tro.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ky ((lang xa) or (dang van)) hoi. hieu qua ca truc va ((dinh vien) OR (dinh viet)) cac tro".
• Adding a wildcard symbol may retrieve word variants: thu sach ky ((lang xa) or (dang van)) hoi. hieu qua ca truc va ((dinh vien) OR (dinh viet)) cac tro*.