Perhaps you should try some spelling variations:
van thanh » ban thanh, van tuan
toc sach » hoc sach, doc sach, thuoc sach
thanh vi » hanh vi, thanh va, thanh ve
tang van » dang van, hoang van, trong van
sach ky » sac ky, sach y, sach ty
cua tre » cua te, cuu tre, cua triet
nang ma » tang ma, sang ma, nang cao
ve cac » va cac, vien cac
ly van » le van, ly va, ly von
vi cua » vai cua, di cua
ve tac » va tac, ve tai

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 ky ((nang ma) or (tang van)) hoi. hieu ((ve tac) OR (ve cac)) ly van thanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky ((nang ma) OR (tang van)) hoi. hieu ((ve tac) OR (ve cac)) ly van thanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ky ((nang ma) or (tang van)) hoi. hieu ((ve tac) OR (ve cac)) ly van thanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: toc sach ky ((nang ma) or (tang van)) hoi. hieu ((ve tac) OR (ve cac)) ly van thanh vi cua tre*.