Perhaps you should try some spelling variations:
cach khuan » cac khoan, cach hoan
thuoc sach » hoc sach, nuoc sach, thuat sach
cach thoi » cac thoi, cach thuc, cach noi
thoi thuc » choi thuc, thai thuc, thi thuc
thuc hang » thuc hanh, thu hang, phuc hang
hang khoa » dung khoa
sach thuc » cach thuc, sach thu, sach thue
thuc thuc » hoc thuc
thuc cach » truoc cach, thuc hanh, tuc cac
khuan hoa » khuan khoa, chuan hoa, nhuan khoa
hoa trong » hoc trong, dot trong, hoa cong
tu cach » tu cac
khoa he » hoa he, khoa hoc, khong he

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( tu cach thoi thuc hang khoa he thong ) or ( thuoc sach thuc thuc cach khuan hoa trong ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu cach thoi thuc hang khoa he thong ) OR ( thuoc sach thuc thuc cach khuan hoa trong )).
• Adding a wildcard symbol may retrieve word variants: (( tu cach thoi thuc hang khoa he thong ) or ( thuoc sach thuc thuc cach khuan hoa trong ))*.