diff --git a/README.md b/README.md
index 23a86449260c5fb9ef8661286d7f006439108ee9..d3b3c7cde396fc36c64f2da182f4828b2efcbc9d 100644
--- a/README.md
+++ b/README.md
@@ -11,4 +11,13 @@ Framework for Monte Carlo simulation of ultra-high energy cosmic rays and electr
 
 ### Applications
 
-[CRbeam](src/app/crbeam) - cosmic ray beam simulation
\ No newline at end of file
+[CRbeam](src/app/crbeam) - cosmic ray beam simulation
+
+### Installation
+
+- Install required libraries to [external](src/external) folder
+<pre><code>
+cd bin
+cmake -S ../src/app/crbeam -B .
+make
+</code></pre>
\ No newline at end of file
diff --git a/src/app/crbeam/README.md b/src/app/crbeam/README.md
index 2a16963a3e789913ee2a3b391d1983feb5a663f0..b1fbd502ab2697e7262e953781742aba767cdb7e 100644
--- a/src/app/crbeam/README.md
+++ b/src/app/crbeam/README.md
@@ -1,6 +1,6 @@
 # CRbeam
 
-Monte Carlo simulation of the the cosmic ray and EM cascade beam propagation.
+Monte Carlo simulation of the cosmic ray and EM cascade beam propagation.
 
 ### Authors:
    Oleg Kalashev and Alexander Korochkin
diff --git a/src/external/README.md b/src/external/README.md
new file mode 100644
index 0000000000000000000000000000000000000000..e3b23a8f7c7c36262d6962747b9faa7ba0f9c9eb
--- /dev/null
+++ b/src/external/README.md
@@ -0,0 +1,8 @@
+# Installing external libraries
+
+<pre><code>
+mkdir SOPHIA
+mkdir nr</code></pre>
+
+- download SOPHIA event generator sources from https://elsevier.digitalcommonsdata.com/datasets/pkx5j87mgn/1 and extract in **SOPHIA** folder
+- download Numerical Recipes 3rd ed. C++ source code from http://numerical.recipes/com/storefront.html and extract to **nr** folder
diff --git a/src/lib/CMakeLists.txt b/src/lib/CMakeLists.txt
index 426232373f1a61fffdec41e31e3b9463301e3619..a8caa232a7b7594be9c9ec1d09c7b8e50795a825 100644
--- a/src/lib/CMakeLists.txt
+++ b/src/lib/CMakeLists.txt
@@ -43,10 +43,7 @@ IF(${CMAKE_SYSTEM_NAME} MATCHES "Linux")
   set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} -rdynamic")
 endif (${CMAKE_SYSTEM_NAME} MATCHES "Linux")
 
-#FIND_LIBRARY(FORTRAN_LIBRARY gfortran PATHS OS/lib)
-#FIND_LIBRARY(OMP_LIBRARY gomp PATHS OS/lib)
 FIND_LIBRARY(C_LIBRARY c)
-FIND_LIBRARY(XERCES_LIBRARY xerces-c)
 FIND_LIBRARY(GSL_LIBRARY gsl)
 FIND_LIBRARY(GSLCBLAS_LIBRARY gslcblas)