In every African country, most businesses operate underground, beyond the reach of regulators and tax collectors.

He operated underground from June 1986 to October 1986, but openly resumed his work despite the continuing state of emergency.

The Outsiders operated illegally and underground with all current members at the time (excluding Nightwing) presumed dead by the general public.

Afterward, he would join the New Avengers, who continue to operate underground without registering.

Several political or cultural Catalan movements operated underground during the dictatorship of Francisco Franco, which lasted until 1975.

It wasn't meant to completely operate underground, but rather as an independent rail system that would also connect different city neighborhoods.

The common characteristic is that all of the trade operates underground, with victims who are in no position to report abuse.

Catholics who insist on being loyal to the Pope can only operate underground, and their number is difficult to estimate.

The Cologne Stadtbahn is not a true subway system, even though a large part of the system operates underground, especially in the downtown area.