Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, lieu va
tay lang » tai lang, tay tang, tay quang
danh va » doanh va, hanh va, anh va
cua tre » cua te, cuu tre, cua triet
xuc va » duc va, luc va, xac va
tuc va » thuc va, truc va, tuc xa
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 ((_ lang) or (tay lang)) xa hoi. hieu van nam ((xuc va) OR (tuc va)) danh va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ((_ lang) OR (tay lang)) xa hoi. hieu van nam ((xuc va) OR (tuc va)) danh va cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ((_ lang) or (tay lang)) xa hoi. hieu van nam ((xuc va) OR (tuc va)) danh va cua tre".
• Adding a wildcard symbol may retrieve word variants: toc sach ((_ lang) or (tay lang)) xa hoi. hieu van nam ((xuc va) OR (tuc va)) danh va cua tre*.