diff --git a/README.md b/README.md
index a146318c..38266bab 100644
--- a/README.md
+++ b/README.md
@@ -7,16 +7,17 @@ NanoVNA - Very tiny handheld Vector Network Analyzer
 
 # About
 
-NanoVNA is very tiny handheld Vector Network Analyzer, works as
-standalone, portable with battery and lcd display. This project aim
-to provide an RF gadget but useful measuring tool for enthusiast.
+NanoVNA is very tiny handheld Vector Network Analyzer (VNA). It is
+standalone with lcd display, portable device with battery. This
+project aim to provide an RF gadget but useful instrument for
+enthusiast.
 
 This repository contains source of NanoVNA firmware.
 
 
 ## Prepare ARM Cross Tools
 
-Install cross tools and dfu-util.
+Install cross tools and firmware updating tool.
 
     $ brew tap PX4/px4
     $ brew install gcc-arm-none-eabi
@@ -26,29 +27,33 @@ Otherwise, use toolchains included inside LPCxpresso. Like this.
 
     $ PATH=$PATH:/Applications/lpcxpresso_7.8.0_426/lpcxpresso/tools/bin
 
-## Building firmware
+## Build the firmware
 
 Fetch ChibiOS submodule into tree.
 
     $ cd nanovna
     $ git submodule update --init --recursive
 
-Enter firmware directory and make it.
+Just make in the top directory.
 
     $ make
 
-## Burn it
+## Burn the firmware
 
-Boot MCU in DFU mode. To do this, jumper BOOT0 pin at powering on.
-And then, burn firmware using dfu-util via USB.
+Boot MCU in DFU mode. To do this, jumper BOOT0 pin at powering device.
+Then, burn firmware using dfu-util via USB.
 
     $ dfu-util -d 0483:df11 -a 0 -s 0x08000000:leave -D build/ch.bin
 
 
-# Control NanoVNA from Host PC
+# Control from PC
 
-NanoVNA is able to work standalone, but also be controlled from host
-PC. python folder contains some sample scripts to control NanoVNA.
+NanoVNA is able to work standalone, but also be controlled via USB serial interface from PC. There are sample scripts in python directory.
+
+Preparation.
+
+    $ pip install numpy
+    $ pip install scikit-rf   
 
 Plot reflection LOGMAG.
 
@@ -67,6 +72,14 @@ Show usage.
 
     $ ./nanovna.py -h
 
-To use nanovna module in Jupyter, see [this page](/python/NanoVNA-example.ipynb).
+To use NanoVNA from Jupyter notebook, see [this page](/python/NanoVNA-example.ipynb).
+
+## Reference
+
+* [Schematics](/doc/nanovna-sch.pdf)
+* [PCB Photo](/doc/nanovna-pcb-photo.jpg)
+* [Block Diagram](/doc/nanovna-blockdiagram.png)
+* Kit available from http://ttrftech.tumblr.com/kit/nanovna
+* Credit: @edy555
 
 [EOF]
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