Synthesis, Characterization, Antibacterial Properties, and In Vitro Studies of Selenium and Strontium Co-Substituted Hydroxyapatite oleh Muhammad Maqbool, Qaisar Nawaz, Muhammad Atiq Ur Rehman, Mark Cresswell, Phil Jackson, Katrin Hurle, Rainer Detsch, Wolfgang H. Goldmann, Asma Tufail Shah, Aldo R. Boccaccini