Instructions for the nearly dozen mail bombs that were sent to critics of President Trump this week may have originated from the internet, according to a new report.

Designs for explosive devices are widely available on websites and propaganda distributed by terror groups al Qaeda and ISIS, a federal law enforcement official who is a bomb expert told Reuters on Thursday.

The blueprint of the bombs that were sent could’ve also been taken from “The Anarchist Cookbook,” a manual dating to the early 1970s, the source said.

A total of 10 packages that contained pipe bombs were sent this week to several high-profile Democrats and staunch Trump critics, as well as actor Robert De Niro and billionaire Democrat George Soros. None of them exploded.

Investigators believe several of the suspicious packages were processed at the Opa-Locka mail facility in southern Florida, CNN reported.