Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
toan cao » toan ban, toan tap
nhan luc » nang luc
cua viet » ca viet, hoa viet, cua vat
lang xa » lang ha, dang xay, lang van
hieu va » lieu va, hieu qua
tao cao » bao cao
nang xa » nang x, nang ma, mang xa
va nhan » van nhan, ca nhan, va phan
luc va » duc va, tuc va, loc va

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 y ((nang xa) or (lang xa)) hoi. hieu va nhan luc va ((tao cao) OR (toan cao)) cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach y ((nang xa) OR (lang xa)) hoi. hieu va nhan luc va ((tao cao) OR (toan cao)) cua viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach y ((nang xa) or (lang xa)) hoi. hieu va nhan luc va ((tao cao) OR (toan cao)) cua viet".
• Adding a wildcard symbol may retrieve word variants: thu sach y ((nang xa) or (lang xa)) hoi. hieu va nhan luc va ((tao cao) OR (toan cao)) cua viet*.