Taxa marked with an asterisk (*) are of doubtful validity.

Two species have been named, but they are of doubtful validity.

But lawyers for the President and his spokesman have repeatedly said he will not appear, and a subpoena would be of doubtful validity.

It was not, instead being designated "of very doubtful validity."

Arguments of doubtful validity have often been put forward to explain this unique phenomenon.

(A previous marriage in Scotland was considered of doubtful validity).

I was risking my life, perhaps more, on an ancient custom of doubtful validity.

Thus, if the water argument of doubtful validity.

This is a distinction that agony aunts commonly make, and is of doubtful validity.

How could a person rate bad dreams if a person never did anything of doubtful validity?