Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hanh tai » thanh tai, hang tai, han tai
thu sach » tu sach, thuat sach, thuoc sach
van hanh » van thanh, ban hanh, van anh
hieu va » lieu va, hieu qua
tuc van » thuc van, truc van, tuc va
cam tuc » cam xuc, cam tu, nam thuc
cuc tre » duc tre, cua tre, cuu tre
hieu ve » hieu van
nang xa » nang x, lang xa, nang ma

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((toc sach) or (thu sach)) ky nang xa hoi. ((hieu ve) or (hieu va)) cam tuc van hanh tai cuc tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (thu sach)) ky nang xa hoi. ((hieu ve) OR (hieu va)) cam tuc van hanh tai cuc tre.
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (thu sach)) ky nang xa hoi. ((hieu ve) or (hieu va)) cam tuc van hanh tai cuc tre*.