How to settle him down

Luke is about 4 or 5. The first few times I worked with him, he was fine. He has a very short attention span, but I would get him to play with something for a couple minutes at a time, and he always loves to play ball. He doesn't speak at all, except for saying, "Ba! Ba!" when he wants the ball, and, "Ma! Ma!" when he wants his mom. When I started actually pushing him and forcing him to sit through looking at a 4-page book with me, or finishing a 4-piece puzzle we had started, he would sometimes get kind of aggressive. Once he threw a book that hit me in the head and left a bump on my forehead for several days. Another day he got mad and started hitting, kicking, and throwing things at me, and somehow I ended up with a cut on my forehead (which I didn't notice till afterwards when someone pointed it out to me). I guess the aggression thing was nothing new though, he's been really aggressive with other staff people a lot. About 6 weeks ago, he started crying. Screaming and crying for his mom the whole evening long. "Ma! Ma!" Interspersed with plenty of tears can be heard throughout the halls. I can sometimes get him to calm down. One night I held him in my arms and rocked him for about 15 minutes, saying, "Shh, it's okay," over and over. And then his was fine for the rest of the time. Of course this used up half of my half hour with him. Another time I just got him really busy doing stuff and he was more or less okay. Blowing bubbles works for a little while. But of course the same thing often doesn't work twice. And even if I get him calmed down, he usually goes back to crying again as soon as I pass him off to the next person. I'll be working with him again tonight. What will work this time?