Perhaps you should try some spelling variations:
cach khong » cach phong, cac phong, bach khang
sach tren » sach tien, sach tranh
tren thuc » trien thuc, tron thuc, trinh thuc
thuc cach » thuoc sach, truoc cach, thuc hanh
khong khi » khong he
khi thong » khi phong, khi tuong, thi thuong
hoc doanh » hoa doanh, hoc danh, hoc dan
doanh hoa » doanh khoa, doanh hoan, danh hoa
bach nha » sach nha, bac nha, bach ha
so sach » so sanh, bo sach, co sach
nha hoc » nha thuoc, khoa hoc, nha nuoc

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( so sach tren thuc cach khong khi thong ) or ( vu bach nha hoc doanh hoa he thong ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( so sach tren thuc cach khong khi thong ) OR ( vu bach nha hoc doanh hoa he thong )).
• Adding a wildcard symbol may retrieve word variants: (( so sach tren thuc cach khong khi thong ) or ( vu bach nha hoc doanh hoa he thong ))*.