APA

Glenn J. H., Letters John Glenn & Glenn J. H. (1964). P.S. I listened to your heartbeat. Houston: World Book Encyclopedia Science Service.

Chicago

Glenn John H, Letters John Glenn and Glenn John H. 1964. P.S. I listened to your heartbeat. Houston: World Book Encyclopedia Science Service.

Harvard

Glenn J. H., Letters John Glenn and Glenn J. H. (1964). P.S. I listened to your heartbeat. Houston: World Book Encyclopedia Science Service.

MLA

Glenn John H, Letters John Glenn and Glenn John H. P.S. I listened to your heartbeat. Houston: World Book Encyclopedia Science Service. 1964.