diff --git a/wp/references.bib b/wp/references.bib
index e34cc5a44..bd9a50f9e 100644
--- a/wp/references.bib
+++ b/wp/references.bib
@@ -1249,3 +1249,20 @@ @inproceedings{Vaucher2009TrackingDS
   title = {{Tracking Design Smells: Lessons From a Study of God Classes}},
   year = {2009},
 }
+
+`@techreport`{ISO25010,
+  title = {Systems and software engineering -- Systems and software Quality Requirements and Evaluation (SQuaRE) -- Product quality model},
+  institution = {International Organization for Standardization},
+  number = {ISO/IEC 25010:2023},
+  year = {2023},
+  url = {https://www.iso.org/standard/78176.html}
+}
+}
+
+@book{Leveson2011,
+  title = {Engineering a Safer World: Systems Thinking Applied to Safety},
+  author = {Leveson, Nancy},
+  year = {2011},
+  publisher = {MIT Press},
+  url = {https://mitpress.mit.edu/9780262016629/engineering-a-safer-world/}
+}
diff --git a/wp/sections/introduction.tex b/wp/sections/introduction.tex
index 2d6bd9890..664af2bf6 100644
--- a/wp/sections/introduction.tex
+++ b/wp/sections/introduction.tex
@@ -24,16 +24,16 @@
 analyze, modify, and adapt given software \citep{Mohammadi2013AnAO}.
 
 Functional quality aspects are typically quite susceptible to formal definition
-and quantification.
-% (\todo: examples!!).
+and quantification. For example, metrics such as defect density measured per 
+thousand lines of code (KLOC), code coverage percentages, or pass/fail rates 
+of functional test suites provide clear, quantifiable measures of functional correctness. 
 Functional quality is also an essential
 requirement in any domain of software development. On the other hand,
-maintainability is a lot less straightforward to formally specify or quantify.
-%\todo: refs.
+maintainability is a lot less straightforward to formally specify or quantify 
+\citep{ISO25010}.
 Also, in certain applications it appears less important than
 functional correctness, although in the business domain it is recognized as an
-essential property.
-% (\todo: ref).
+essential property \citep{Leveson2011}.
 As a result, there is currently a lot more
 research and practical tools addressing functional quality aspects of code than
 maintainability \citep{Overview_Static_Code_Analysis_in_Software_Development}.
@@ -66,8 +66,6 @@
 
 
 
-
-
 % This document explains how Aibolit works  and what makes it novel and
 % different from other static analyzers (Section~\ref{sec:method}).
 % We further show how Aibolit can be extended