Perhaps you should try some spelling variations:
doc sach » hoc sach, toc sach, nuoc sach
nang tao » sang tao, nang tai, nang giao
gia phan » gia nhan, gia pha, gia thanh
phan lap » phan dau
hieu va » lieu va, hieu qua
va pham » van pham, va phat, va phap
duc gia » quoc gia
cua tu » cua tuc, cua su, cua cu

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

• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach y ((nang tao) OR (nang cao)) hoi. hieu va pham duc gia phan lap ((cua te) OR (cua tu))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc sach y ((nang tao) OR (nang cao)) hoi. hieu va pham duc gia phan lap ((cua te) or (cua tu))~".
• Adding a wildcard symbol may retrieve word variants: doc sach y ((nang tao) OR (nang cao)) hoi. hieu va pham duc gia phan lap ((cua te) or (cua tu))*.