Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
tay lang » tai lang, tay tang, tay quang
ty lang » ty xang, ty hang, tu lang
van dam » van nam, van dao, van dau
van lam » van nam
va hanh » van hanh, va thanh, va danh
hanh va » hang va, hanh vi
cua tre » cua te, cuu tre, cua triet
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: toc sach ((ty lang) OR (tay lang)) xa hoi. hieu ((van dam) or (van lam)) duc va hanh va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ((ty lang) OR (tay lang)) xa hoi. hieu ((van dam) OR (van lam)) duc va hanh va cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ((ty lang) OR (tay lang)) xa hoi. hieu ((van dam) or (van lam)) duc va hanh va cua tre".
• Adding a wildcard symbol may retrieve word variants: toc sach ((ty lang) OR (tay lang)) xa hoi. hieu ((van dam) or (van lam)) duc va hanh va cua tre*.