RT Journal Article SR Electronic T1 Ice crystal markings JF American Journal of Science JO Am J Sci FD American Journal of Science SP 494 OP 500 DO 10.2475/ajs.s5-11.66.494 VO s5-11 IS 66 A1 John Andrew Allan YR 1926 UL http://www.ajsonline.org/content/s5-11/66/494.abstract AB