The preferred width of submitted line drawings is 20 to 23 cm, with lettering 4 mm high, for reduction by one-half. Photographs intended for halftone reproduction should be about twice the desired size. No art will be reproduced in color. Figures submitted in color will be reproduced in black and white. It is helpful to identify unusual or ambiguous symbols in the margin when they first occur.
Metric units are preferred.
Avoid the use of vertical rules in tables. Indicate an approximate position for each in the margin. Indicate references in the text by consecutive superior arabic numbers enclosed in square brackets. Collect and type the full list on a separate page at the end of the paper. Information concerning grant support of research should appear in a separate Acknowledgments section at the end of the paper, not in a footnote.