BALLOU, DONALD H.
Spherical trigonometry with tables by Donald H. Ballou & Frederick H. Steen. NM: additions & revisions.
BALLOU, DONALD H. Spherical trigonometry with tables by Donald H. Ballou & Frederick H. Steen. NM: additions & revisions. © 19Nov43; A180240. Donald H. Ballot & Frederick H. Steen (A); 13Jan71; R498447.
Donald H. Ballot & Frederick H. Steen|A