Perhaps you should try some spelling variations:
van thanh » ban thanh
sach thu » sach thue, sach thieu, sach tham
nang dau » hang dau, xang dau, nang du
van tuan » van quan, van ban, anh tuan
tai cua » thai cua, tai cuc, tri cua
hieu ve » hieu va, hieu van
cam duc » cam xuc, cao duc, pham duc
sach ky » sac ky, sach y, sach ty
dau hoi » cau hoi, dai hoi, dan hoi
cua tre » cua te, cuu tre, cua triet
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) or (sach thu)) nang dau hoi. hieu ve cam duc ((van thanh) OR (van tuan)) tai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ky) OR (sach thu)) nang dau hoi. hieu ve cam duc ((van thanh) OR (van tuan)) tai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach ky) or (sach thu)) nang dau hoi. hieu ve cam duc ((van thanh) OR (van tuan)) tai cua tre".
• Adding a wildcard symbol may retrieve word variants: su ((sach ky) or (sach thu)) nang dau hoi. hieu ve cam duc ((van thanh) OR (van tuan)) tai cua tre*.