Perhaps you should try some spelling variations:
sach trinh » sach tranh, hanh trinh, sach kinh
cach khoan » cac khoan, cach hoan, bach khoa
trinh thue » trinh thuc, tinh thue, trinh thuy
sach tren » sach tien, sach tranh
tren thuc » trien thuc, tron thuc, trinh thuc
thuc cach » thuoc sach, truoc cach, thuc hanh
khoan pho » khoan nhoi, khoan phai, khoan hoi
pho thong » he thong
thue dat » thue da, thue luat, thue xuat
dat khoa » da khoa, vat khoa, dac khoa
khoa pho » khoa phu, khoa khoa, khoa phau
tu sach » thu sach, su sach, tu cach
te sach » toc sach

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( tu sach tren thuc cach khoan pho thong ) or ( te sach trinh thue dat khoa pho thong ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu sach tren thuc cach khoan pho thong ) OR ( te sach trinh thue dat khoa pho thong )).
• Adding a wildcard symbol may retrieve word variants: (( tu sach tren thuc cach khoan pho thong ) or ( te sach trinh thue dat khoa pho thong ))*.