1. Ahmed S.—Effect of capping on the compressive strength of concrete cubes. Magazine of Concrete Research 6 (1955):9.
2. Axon E. O.—A method of Estimating the original Mix Composition of Hardened Concrete Using Physical Tests. A.S.T.M. Proceedings, Vol. 62, 1962.
3. Bernander K. G.—Provning av hardnad betong (Testing of Hardened Concrete). Nordisk Betong, 5 (1961):3.
4. Bhargava J. K.—Strength of Concrete in Members Cast in Deep Forms. National Swedish Building Research, No. 5, Stockholm, 1969.
5. Bloem D. L.—Concrete Strength Measurement. Cores vs Cylinders. A.S.T.M. Proceedings, Vol. 65, 1965.