Study on American legal system of software patent protection 并列题名:Study on American legal system of software patent protection Research on the legal system of cultivated land protection Study on the legal system of trust taxation Study on legal system of network lawful interception Study on the legal system of red line for the ecological protection Research on legal system of patent transaction 并列题名:Research on legal system of patent transaction Study on legal system of women's rights and interests protection Research on the international legal system of diplomatic protection