Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
thanh vi » hanh vi, thanh va, thanh ve
cua quoc » cua nuoc, cua thuoc
nang mai » nang ma, nang tai, lang mai
thu sach » tu sach, thuat sach, thuoc sach
mai hoi » mai khoi, dai hoi, lai hoi
hieu va » lieu va, hieu qua
xuc van » duc van, vuc van, xuc ban
luc van » luoc van, luu van, duc van
y nang » ky nang, ly nang, v nang
vi cua » vai cua, di cua
va cao » va cac, va co, va dao

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)) y nang mai hoi. hieu va cao ((xuc van) or (luc van)) thanh vi cua quoc~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (thu sach)) y nang mai hoi. hieu va cao ((xuc van) OR (luc van)) thanh vi cua quoc.
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (thu sach)) y nang mai hoi. hieu va cao ((xuc van) or (luc van)) thanh vi cua quoc*.