Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
nang mai » nang ma, nang tai, lang mai
tu cach » tu cac
va hanh » van hanh, va thanh, va danh
cam tuc » cam xuc, cam tu, nam thuc
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu van
mai hoi » mai khoi, dai hoi, lai hoi
tuc va » thuc va, truc va, tuc xa
vi cua » vai cua, di cua

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

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