Some of Luke's Available Sources for Acts

Regarding: Eyewitness Source: Comment:
Events in the early Jerusalem church. Mary, the Mother of Jesus She was present during this time. Acts 1:14. Luke had talked with her when preparing to write the Gospel of Luke. See Luke 2:19,51.
Selecting the seven, the events in Samaria and with the Eunuch. Philip Luke was at his house and could have recorded the events. 21:8 Luke probably stayed with Philip while Paul was imprisoned at Caesarea in Acts 24 - 26.
Events at Jerusalem. James, the Lord's Brother He wrote James. He was with Luke at Jerusalem. Acts 21:18
Events relating to Peter's life and travels. Peter While we lack hard evidence that Luke met with Peter, we assume that these men knew each other.
Events about Stephen, Paul's own conversion and from chapter 13 - end. Paul Luke was Paul's traveling companion. They were together in Rome when Acts was written.
The Second Missionary Journey. Silas He co-authored 1,2 Thess. See 1:1 of each.
Luke was with Silas at Philippi. Acts 16.
The Second Missionary Journey. Timothy He co-authored 1,2 Thess. See 1:1 of each.
Luke was with Timothy in Acts 20:4,5.
The Second Missionary Journey to the end of the book. Luke's own observations He previously wrote the Gospel of Luke.