Perhaps you should try some spelling variations:
thanh hai » thanh phan, thanh hoa
toc sach » hoc sach, thuoc sach, nuoc sach
doc sach » hoc sach, nuoc sach, dac sac
dua ban » dia ban, cua ban, qua ban
cuc tre » duc tre, cua tre, cuu tre
hieu ve » hieu va, hieu van
cao hoi » cau hoi, co hoi, cao hoc
ty nang » ky nang, ty xang, ty hang
ca dua » cay dua, ca cua, ca da
ve ca » ve cac, ve cai, ve cau

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) or (doc sach)) ty nang cao hoi. hieu ve ca dua ban ((thanh hai) OR (thanh san)) cuc tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (doc sach)) ty nang cao hoi. hieu ve ca dua ban ((thanh hai) OR (thanh san)) cuc tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) or (doc sach)) ty nang cao hoi. hieu ve ca dua ban ((thanh hai) OR (thanh san)) cuc tre".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (doc sach)) ty nang cao hoi. hieu ve ca dua ban ((thanh hai) OR (thanh san)) cuc tre*.