Perhaps you should try some spelling variations:
thanh hai » thanh phan, thanh hoa
thu sach » tu sach, thuat sach, thuoc sach
vu kham » vu khanh
kham le » pham le
hieu vu » hieu va, hieu ve, hieu su
sach ky » sac ky, sach y, sach ty
mai hoi » mai khoi, dai hoi, lai hoi
cua tre » cua te, cuu tre, cua triet
ma hoi » xa hoi, ma hoa, me hoi

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach ky nang ((ma hoi) or (mai hoi)). hieu vu kham le van ((thanh hai) OR (thanh san)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky nang ((ma hoi) OR (mai hoi)). hieu vu kham le van ((thanh hai) OR (thanh san)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ky nang ((ma hoi) or (mai hoi)). hieu vu kham le van ((thanh hai) OR (thanh san)) cua tre".
• Adding a wildcard symbol may retrieve word variants: thu sach ky nang ((ma hoi) or (mai hoi)). hieu vu kham le van ((thanh hai) OR (thanh san)) cua tre*.