1. The Design of Masonry Structures and Foundations by C. C. Williams . 2nd Edition 1930 Page 479 .
2. Civil Engineering Handbook 2nd Edition 1940 page 644 by L. C. Urquhart.
3. Bulletin No. 3 Engineering Experiment Station. North Carolina State College August 1929 .
4. Embedment of Poles Sheeting and Anchor Piles by M. A. Drucker Vol. 4 No. 12 Civil Engineering for Dec ember 1934.
5. Lateral Pile Loading Tests by L. B. Feagin with discussion by A. E Cummings J . C . Meen T. Keinnard Thomson August E . Niederhoff Lazarus White Y. L . Chang D. P. Krynine . Paper No . 1959 Vol. 102 1937 Transactions of ASCE .