Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
van hanh » van thanh, ban hanh, van anh
truc van » truc va, thuc van, truc ban
nam truc » nam truoc, nam thuc, nam trung
su sach » so sach, vu sach
hanh va » hang va, hanh vi
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
nang co » nang cao, nang doc, nang noi
nang ro » nang ho, nang ra, nang rong
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: ((su sach) or (toc sach)) ky ((nang ro) or (nang co)) hoi. hieu va nam truc van hanh va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (toc sach)) ky ((nang ro) OR (nang co)) hoi. hieu va nam truc van hanh va cua tre.
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (toc sach)) ky ((nang ro) or (nang co)) hoi. hieu va nam truc van hanh va cua tre*.