diff --git a/sources.tex b/sources.tex
index 6bd05fb..80685fb 100644
--- a/sources.tex
+++ b/sources.tex
@@ -25,5 +25,7 @@
    \bibitem{links:scipy_doc} Scipy API Reference [Электронный ресурс] -- URL:~\url{https://docs.scipy.org/doc/scipy/reference/index.html} (\LiteratureAccessDate[3]).
    \bibitem{links:tiobe_index} TIOBE. Официальный сайт проекта
    [Электронный ресурс] -- URL:~\url{https://www.tiobe.com/tiobe-index/} (\LiteratureAccessDate).
-   \bibitem{journal:cartwright} Simpson's Rule Cumulative Integration with MS Excel and Irregularly-spaced Data / Cartwright, Kenneth V.  // Journal of Mathematical Sciences and Mathematics Education. -- Vol.~12 --  P.~1-9
+   \bibitem{journal:cartwright} Simpson's Rule Cumulative Integration with MS Excel and Irregularly-spaced Data / Cartwright, Kenneth V.  // Journal of Mathematical Sciences and Mathematics Education. -- 2017. -- Vol.~12~(2) -- P.~1-9.
+   \bibitem{article:fehlberg} Classical Fifth-, Sixth-, Seventh-, and Eighth-Order Runge-Kutta Formulas with Stepsize Control / Fehlberg E. // NASA technical report 287 -- 1968.
+   -- P.~82
 \end{thebibliography}