RT Journal Article SR Electronic T1 A contribution to Croll's theory of secular climatal changes JF American Journal of Science JO Am J Sci FD American Journal of Science SP 437 OP 443 DO 10.2475/ajs.s3-22.132.437 VO s3-22 IS 132 A1 W J [i. e. William John] McGee YR 1881 UL http://www.ajsonline.org/content/s3-22/132/437.abstract AB