Perhaps you should try some spelling variations:
thanh va » thanh van, hanh va, thanh ha
toc sach » hoc sach, doc sach, thuoc sach
va thanh » gia thanh, ban thanh, va tinh
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, su sach, te sach
cac xuc » cam xuc, cac nuoc, chat xuc
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu va
tang ma » mang may, tang van
ky tang » ky nang, ky dang, kho tang
ma hoi » mai hoi, xa hoi, ma hoa
xuc va » duc va, tuc va, luc va
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: ((tu sach) or (toc sach)) ky tang ma hoi. ((hieu ve) OR (hieu van)) cac xuc va thanh va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (toc sach)) ky tang ma hoi. ((hieu ve) OR (hieu van)) cac xuc va thanh va cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (toc sach)) ky tang ma hoi. ((hieu ve) OR (hieu van)) cac xuc va thanh va cua tre".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (toc sach)) ky tang ma hoi. ((hieu ve) OR (hieu van)) cac xuc va thanh va cua tre*.