Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
nam thuc » nam thuoc, am thuc, nam thu
hieu va » lieu va, hieu qua
hanh va » hang va, hanh vi
va hanh » van hanh, va thanh, va danh
thuc va » thuc vat, thuc dan, thuc day
tu sach » thu sach, su sach, te sach
nang ma » tang ma, sang ma, nang cao
bo sach » co sach, hoc sach
cua tre » cua te, cuu tre, cua triet
ma hoi » mai hoi, xa hoi, ma hoa
va nam » van nam, ha nam, va nay
va cua » va chua, via cua, ca 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 sach) or (bo sach))) or (toc sach)) ky nang ma hoi. hieu va nam thuc va hanh va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((((tu sach) OR (bo sach))) OR (toc sach)) ky nang ma hoi. hieu va nam thuc va hanh va cua tre.
• Adding a wildcard symbol may retrieve word variants: ((((tu sach) or (bo sach))) or (toc sach)) ky nang ma hoi. hieu va nam thuc va hanh va cua tre*.