There doesn't seem to have much informations on Internet, so I'm wondering if historians could point to some books worth reading ?
That's a great question, and it's especially interesting in light of the two shiploads full of Swedish corpses found at Salme, Estonia. They're probably from the 600s, which is a bit earlier than what we typically call the "Viking Age," but it seems like these were nevertheless early viking raiders who had a very unlucky day. There's a new research project that will hopefully tell us a lot more about these Swedish raiders, and maybe even completely change how we think about the Viking Age. Until then, however, there's a number of articles out, and some of these can be found by searching for their titles online:
Jüri Peets, Raili Allmäe, and Liinda Maldre, "Archaeological Investigations of Pre-Viking Age Burial Boat in Salme Village at Saaremaa," Archaeological Fieldwork in Estonia (2010): 29-48.
Raili Allmäea, Liina Maldrea, Teresa Tomek, "The Salme I Ship Burial: An Osteological View of a Unique Burial in Northern Europe," Interdisciplinaria Archaelogica. Natural Sciences in Archaeology 2.2 (2011): 97-112.
Jüri Peets et al., "Research Results of the Salme Ship Burials in 2011-2012," Archaeological Fieldwork in Estonia (2012): 1-18.
For broader surveys that include important information on Viking Age Estonia, there's a few places to check. I'd caution that—at least in the English language literature with which I'm most familiar—there's not much available, and there's lots we just don't know. It looks like there were a few people from present-day Scandinavia moving back and forth to Estonia, and it looks like there were a few people from Estonia participating in the "viking" culture of the Baltic Sea, and perhaps even joining in viking raids in Western Europe. To get some idea of the current state of knowledge, although neither of these books has an extended discussion of Estonia, I'd recommend:
Wladyslaw Duczko, Viking Rus: Studies on the Presence of Scandinavians in Eastern Europe, Northern World 12 (Leiden: Brill, 2004).
Anton Englert and Athena Trakadas, eds., Wulfstan’s Voyage: The Baltic Sea Region in the Early Viking Age as Seen from Shipboard, Maritime Culture of the North 2 (Roskilde: Viking Ship Museum, 2009).