Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
cac hoc » cach hoc, bac hoc, cac toc
va hanh » van hanh, va thanh, va danh
sach ty » sach y, sach tu, sach thu
hieu ve » hieu va, hieu van
nang xa » nang x, lang xa, nang ma
ty nang » ky nang, ty xang, ty hang
va huu » vu huu
va chi » van chi, va che, va cai

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 ty nang xa hoi. hieu ve ((cac hoc) OR (cac hop)) va hanh ((va huu) or (va chi)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty nang xa hoi. hieu ve ((cac hoc) OR (cac hop)) va hanh ((va huu) OR (va chi)) tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty nang xa hoi. hieu ve ((cac hoc) OR (cac hop)) va hanh ((va huu) or (va chi)) tre*".