1. Research Hydr. Engr., United States Dept. of Agr., Sci. and Education Administration, Agricultural Research, St. Anthony Falls Hydr. Lab., Third Avenue Southeast at Mississippi River, Minneapolis, Minn. 55414
2. Research Hydr. Engr., United States Dept. of Agr., Sci. and Education Administration, Agricultural Research, St. Anthony Falls Hydr. Lab., Third Avenue Southeast at Mississippi River, Minneapolis Minn. 55414
3. Hydr. Engr., United States Dept. of Agr., Sci. and Education Administration, Agricultural Research, St. Anthony Falls Hydr. Lab., Third Avenue Southeast at Mississippi River, Minneapolis, Minn. 55414