Add references

thesis/bib/bibliography.bib

@@ -594,4 +594,28 @@
   note         = {Online, accessed 22.03.2019},
 }
 
+@Book{kurose2005computer,
+  title     = {Computer networking: A top-down approach featuring the internet, 3/E},
+  publisher = {Pearson Education India},
+  year      = {2005},
+  author    = {Kurose, James F},
+}
+
+@Book{tanenbaum2007distributed,
+  title     = {Distributed systems: principles and paradigms},
+  publisher = {Prentice-Hall},
+  year      = {2007},
+  author    = {Tanenbaum, Andrew S and Van Steen, Maarten},
+}
+
+@Book{Tanenbaum:2010:CN:1942194,
+  title     = {Computer Networks},
+  publisher = {Prentice Hall Press},
+  year      = {2010},
+  author    = {Tanenbaum, Andrew S. and Wetherall, David J.},
+  address   = {Upper Saddle River, NJ, USA},
+  edition   = {5th},
+  isbn      = {0132126958, 9780132126953},
+}
+
 @Comment{jabref-meta: databaseType:bibtex;}

thesis/content/02-background/p2p.tex

@@ -1,6 +1,6 @@
 The distinctive feature of \ac{P2P} systems is that each participant has the role of both a server and a client. The participants are therefore equal and provide each other with services, what is reflected in the naming. \ac{P2P} networks are usually characterized as overlay networks over the Internet. Concerning the structure of the overlay network, a distinction is made between structured and unstructured networks. The \ac{P2P} principle became well-known in 1999 with the file-sharing application Napster. The software connected its users and allowed accessing (mainly copyrighted) songs among the participants without having to offer them from a central server. Popular applications of \ac{P2P} networks are file sharing (e.g., BitTorrent), instant messaging (e.g., Skype) and blockchain technology (e.g., Bitcoin).
 
-Their independence particularly characterizes \ac{P2P} networks: there are no control points and not necessarily a fixed infrastructure which leads to minimal operating costs. Besides, \ac{P2P} networks are self-organized and self-scaling, as each additional user contributes its resources. However, there are also some challenges in \ac{P2P} networks that need to be solved for successful operation. These include finding peers in the network (peer discovery) and finding resources (resource discovery). Especially in file sharing networks, solutions have to be found how to motivate users to upload data and not only use the download one-sidedly. The replication of data and the associated availability must also be taken into account in solutions. Another critical issue is the Internet connection of individual participants, which may not be powerful or permanent.
+Their independence particularly characterizes \ac{P2P} networks: there are no control points and not necessarily a fixed infrastructure which leads to minimal operating costs. Besides, \ac{P2P} networks are self-organized and self-scaling, as each additional user contributes its resources. However, there are also some challenges in \ac{P2P} networks that need to be solved for successful operation. These include finding peers in the network (peer discovery) and finding resources (resource discovery). Especially in file sharing networks, solutions have to be found how to motivate users to upload data and not only use the download one-sidedly. The replication of data and the associated availability must also be taken into account in solutions. Another critical issue is the Internet connection of individual participants, which may not be powerful or permanent. \cite{tanenbaum2007distributed,Tanenbaum:2010:CN:1942194,kurose2005computer}
 
 \subsection{Unstructured \ac{P2P} Networks}
 \label{sec:unstructured-p2p}

thesis/content/02-background/software-system-architecture.tex

@@ -1,4 +1,4 @@
-The software system architecture describes the relationships and properties of individual software components. It is a model that describes a software on a high-level design. The structure of an architecture can be represented mathematically as a graph, with the nodes representing the individual software components and the edges their relationships to each other. Although the individual components can be executed on the same computer, they are usually interconnected via networks. In general, a distinction is made between centralized, decentralized and distributed architectures as shown in Figure \ref{fig:software-system-architecture}. In the following, the characteristics and peculiarities of the different architectures are described in detail.
+The software system architecture describes the relationships and properties of individual software components. It is a model that describes a software on a high-level design. The structure of an architecture can be represented mathematically as a graph, with the nodes representing the individual software components and the edges their relationships to each other. Although the individual components can be executed on the same computer, they are usually interconnected via networks. In general, a distinction is made between centralized, decentralized and distributed architectures as shown in Figure \ref{fig:software-system-architecture}. In the following, the characteristics and peculiarities of the different architectures are described in detail. \cite{Tanenbaum:2010:CN:1942194, kurose2005computer}
 
 \begin{figure}[h!]
 	\centering