Do you want literature for commercial hydroponics or laboratory
research on plants using solution culture? If you want laboratory
research methods, try PubMed Central:

http://www.pubmedcentral.nih.gov/

A recent book on commercial hydroponics is:

Jones, J. B. Jr. 2004. Hydroponics: A Practical Guide for the Soilless
Grower, Second Edition. CRC Press.

A recent college mineral nutrition text has basic info on plant
solution cultu

Epstein, E. and Bloom, A. 2004. Mineral Nutrition of Plants: Principles
and Perspectives. Sinauer Associates.

The extensive classic review of solution culture research techniques
is:

Hewitt, E.J. 1966. Sand and water culture methods used in the study of
plant nutrition. Technical communication of the Commonwealth Bureau of
Horticulture and Plantation Crops.

You might check Annual Review of Plant Physiology and Molecular Biology
and Horticultural Reviews.

If you want information for teaching projects on hydroponics, I can
email a copy of my review:

Hershey, D.R. 1994. Solution culture hydroponics: history and
inexpensive equipment. American Biology Teacher 56:111-118.

Amazon.com is another good source to find more books on these topics.

David R. Hershey