diff --git a/materials_and_surfaces.md b/materials_and_surfaces.md
index 3fe1fee..4cb2d22 100644
--- a/materials_and_surfaces.md
+++ b/materials_and_surfaces.md
@@ -1,8 +1 @@
-## References:
-
-Finckenor, Miria M. 2016. “Materials for Spacecraft. Chapter 6.” https://ntrs.nasa.gov/search.jsp?R=20160013391.
-
-Dunn, Barrie D. 2016. Materials and Processes: For Spacecraft and High Reliability Applications. https://www.springer.com/gp/book/9783319233611
-
-Pereira, A. M., G. Pimenta, and B. D. Dunn. 2008. “Assessment of Chemical Conversion Coatings for the Protection of Aluminium Alloys.” ESA Scientific & Technical Memoranda 276.
-“Pereira et al. - 2008 - Assessment of Chemical Conversion Coatings for the.Pdf.” n.d. Accessed January 19, 2018. http://esmat.esa.int/ESA-STM-276.pdf.
+see [vacuum.md](vacuum.md)