They are so called because each plays with a different concept of time.

But then the concept of time was not as well developed, either.

Often the contracts did away with the concept of over time at increased rates.

The concept of time was not the same in here.

He wasn't certain, for at first he'd had but a vague concept of time.

Although not the first to do so, 24 embraced the concept of real time.

He had no concept of time and wasn't bothered with it.

Children basically have no concept of time until they reach a certain age.

Why is it that small children have such difficulty understanding the concept of time?

The concept of time is present throughout the whole novel.