These people said that they never used an alarm or other external means to wake up.

The former is an external means of communication, essential in describing something probably outside the usual reader's knowledge, very good for textbooks.

But, more important, writing would allow humans to rely too much on these external means of recording.

Again the heat needed to provide sufficient vapor pressure was produced by external means.

And the only external means I had was reading.

Other external means of declaring encoding are permitted but rarely used.

Also, the projectile needs either an internal or external means to stabilize on orbit.

Parliament has, with this report, made it unmistakeably clear that democratic change cannot be brought about by external military means.

It may then be necessary to use external means to modulate the signal.

Suspended animation is the slowing of life processes by external means without termination.