Perhaps you should try some spelling variations:
sach tranh » canh tranh
tranh thuc » trinh thuc, trang thuc, thanh thuy
sanh trong » sinh trong, anh trong, hanh trong
trong thuc » trong thu, thuong thuc, trong thuat
hoi trong » choi trong, doi trong, nuoi trong
thuc cac » thuc cach, tuc cac, phuc cac
khoan he » khoa he, khoan ke, khoan le
cac khoa » cac khoi, dac khoa, cao khoa
khoa hoi » khoan hoi, khoa hoc, khoa doi
su sach » so sach, vu sach
su sanh » so sanh, su anh, su thanh

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 tranh thuc cac khoan he thong ) or ( su sanh trong thuc cac khoa hoi trong ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( su sach tranh thuc cac khoan he thong ) OR ( su sanh trong thuc cac khoa hoi trong )).
• Adding a wildcard symbol may retrieve word variants: (( su sach tranh thuc cac khoan he thong ) or ( su sanh trong thuc cac khoa hoi trong ))*.