diff --git a/README.md b/README.md
index df9f643..5e598e4 100644
--- a/README.md
+++ b/README.md
@@ -8,7 +8,12 @@
 | Country of Origin                          | China                                |
 | Vendor’s calibration<br>radioactive source | Co-60                                |
 | Sensitivity                                | 44 CPS at 1 mR/h<br>Co-60            |
-| Dead Time                                  | TBD                                  |
+| Dead Time                                  | 180 microseconds*                    |
 | At the background level                    | 25 pulses/minute                     |
 | Internal background <br>noise              | 0,2 pulses/s<br>12 pulses/minute     |
-| Recommended operating<br>supply voltage    | glass tube 380 V<br>metal tube 400 V |
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+| Recommended operating<br>supply voltage    | glass tube 380 V<br>metal tube 400 V |
+
+> *Dead Time for J305 based on the data from the Internet, since the datasheets from suppliers do not contain this data.
+
+### Resources
+- https://iot-devices.com.ua/
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