diff --git a/readme.md b/readme.md
index 2ae5a05..93c46b7 100644
--- a/readme.md
+++ b/readme.md
@@ -8,6 +8,8 @@
 - [AT commands](https://www.sparkfun.com/datasheets/Widgets/ELM327_AT_Commands.pdf)
 - [ELMduino project](https://github.com/PowerBroker2/ELMduino)
 - [Connect ELM327 with HC05](https://www.instructables.com/Arduino-OBD2-ELM327-I2C-LCD-HC05-Bluetooth/)
+- [Datasheet](https://cdn.sparkfun.com/assets/learn_tutorials/8/3/ELM327DS.pdf)
+- [OBD2 PIDs](https://en.wikipedia.org/wiki/OBD-II_PIDs)
 
 ### FSC-BT836B
 - [Datasheet](https://www.feasycom.com/datasheet/fsc-bt836b.pdf)
@@ -18,4 +20,4 @@
 ### 3.5 inch TFT display
 - [Product link](https://www.tinytronics.nl/shop/en/displays/tft/3.5-inch-tft-display-320*480-pixels-mega-compatible-ili9486)
 - [UTFT library](http://www.rinkydinkelectronics.com/library.php?id=51)
-- [SdFat library](https://github.com/greiman/SdFat)
\ No newline at end of file
+- [SdFat library](https://github.com/greiman/SdFat)