Bulk IP abuse reporting

Hi all, It seems that outdated CLDAP servers on the internet are being used again for DDoS amplification attacks. I've got about 16k IPs that have participated in several of these over the last several weeks and I'd like to report these to the relevant abuse departments so they can be properly handled. However, I am not finding a simple, or standardized way to look up the abuse contacts for a specific IP. Does someone have a suggestion? thanks! -- micah