The following figures are not confirmed by serious academic sources or researchers, and are difficult to verify.

Listen Guardian, you need to clean up your act big time if you want to remain a serious source of news.

The technology is useful but is also a serious source of air pollution.

There are also serious sources of increased tension in Russia.

Criticism from a more serious source also challenges Bush's mental outlook.

Trade had become a serious source of friction between the two countries.

Hence, his memoirs are not now considered to be a serious historical source.

More than 1.5 million citizens are living in refugee camps, posing a serious source of risk to public health and safety.

The most serious sources of internal bleeding due to trauma are: