Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
dang hai » dang khai, hang hai, dung hai
hai cua » thai cua, dai cua, hoi cua
hieu ve » hieu va, hieu van
cua tre » cua te, cuu tre, cua triet
ty lang » tay lang, ty xang, ty hang
lang xa » lang ha, dang xay, lang van
xuc va » duc va, luc va, xac va
tuc va » thuc va, truc va, tuc xa
ve cam » ve cham, ve cac, va cam

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: ((te sach) OR (toc sach)) ty lang xa hoi. hieu ve cam ((xuc va) or (tuc va)) dang hai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) ty lang xa hoi. hieu ve cam ((xuc va) OR (tuc va)) dang hai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) OR (toc sach)) ty lang xa hoi. hieu ve cam ((xuc va) or (tuc va)) dang hai cua tre".
• Adding a wildcard symbol may retrieve word variants: ((te sach) OR (toc sach)) ty lang xa hoi. hieu ve cam ((xuc va) or (tuc va)) dang hai cua tre*.