diff --git a/README.md b/README.md
index 6b3c3e2..ae6a165 100644
--- a/README.md
+++ b/README.md
@@ -24,6 +24,10 @@
      Info to noise reduction algorithms: info: https://en.wikipedia.org/wiki/Moving_average
      Calculator used for FIR filters: https://www.arc.id.au/FilterDesign.html
   
+   Additional infos could be found in file How_To_Make.doc, this is a work in progress file
+   where are describing a simple external components board needed to build the DSP filter.
+   The pre-compiled firmware are committed in folder pre-compiled.
+   
    The RadioDSP use some parts of the ARM Cortex Microcontroller Software
    Interface Standard (CMSIS).
    The RadioDSP use some parts of STM32F103 examples by Yohanes Erwin and