After meeting again in 1939, they began to exchange letters.

The two became very close friends and often exchanged letters.

For nearly 20 years, until White's death in 1977, the two women exchanged letters.

Though he could not stay more than a few days, the pair would exchange letters for the next eight years.

The pair exchanged letters with each other until the end of 1882.

A friend and I have been exchanging letters for 20 years now.

The couple started to exchange letters and, with time, poems.

Since then, they have spoken on the phone and exchanged letters.

They exchanged letters for almost 10 years before he asked her to marry him.

They decide to exchange letters to each other after he is deployed to the war.