Perhaps you should try some spelling variations:
doc sach » hoc sach, toc sach, nuoc sach
hieu van » hieu va, thien van, lieu va
nam thuc » nam thuoc, nam thu, nam tu
thanh do » thanh de, thanh hoa, thanh loi
sach ty » sach y, sach tu, sach thu
ty nang » ky nang, ty xang, ty hang
nang xa » nang x, lang xa, nang ma
cua tu » cua tuc, cua su, cua cu

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc sach ty nang xa hoi. hieu van ((nam thuc) or (am thuc)) day ((thanh do) or (thanh pho)) cua tu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach ty nang xa hoi. hieu van ((nam thuc) OR (am thuc)) day ((thanh do) OR (thanh pho)) cua tu.
• Adding a wildcard symbol may retrieve word variants: doc sach ty nang xa hoi. hieu van ((nam thuc) or (am thuc)) day ((thanh do) or (thanh pho)) cua tu*.