Perhaps you should try some spelling variations:
sach truc » cach thuc, sach tren, sach thu
dai tuong » dai cuong, doi tuong, dai duong
hieu thuc » hieu thuoc, hien thuc, lieu thuc
truc tue » truc tu, truc tuyen, truc tiep
hieu tuc » hieu luc, hieu thuoc, lieu thuc
tu sach » thu sach, su sach, te sach
tue dai » tre dai, thue dat, truc dai

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

• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach truc tue dai tuong ((hieu tuc) OR (hieu thuc)) giai~".
• Adding a wildcard symbol may retrieve word variants: tu sach truc tue dai tuong ((hieu tuc) OR (hieu thuc)) giai*.