Perhaps you should try some spelling variations:
thanh hai » thanh phan, thanh hoa
su sach » so sach, vu sach
cam duc » cam xuc, cao duc, pham duc
duc ban » duc tan, duc van, dua ban
cua tre » cua te, cuu tre, cua triet
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
tang ma » tang van
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: su sach ky ((tang ma) or (mang may)) hoi. hieu ve cam duc ban ((thanh hai) OR (thanh san)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky ((tang ma) OR (mang may)) hoi. hieu ve cam duc ban ((thanh hai) OR (thanh san)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky ((tang ma) or (mang may)) hoi. hieu ve cam duc ban ((thanh hai) OR (thanh san)) cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ky ((tang ma) or (mang may)) hoi. hieu ve cam duc ban ((thanh hai) OR (thanh san)) cua tre*.