This artice is free to access.
Saunders, N. F. W., Brinkworth, R. I., Huber, T., Kemp, B. E., & Kobe, B. (2008). Predikin and PredikinDB: A computational framework for the prediction of protein kinase peptide specificity and an associated database of phosphorylation sites. BMC Bioinformatics, 9. https://doi.org/10.1186/1471-2105-9-245