diff --git a/docs/class-diagram.png b/docs/class-diagram.png
index 6aa233d..6eea4fe 100644
Binary files a/docs/class-diagram.png and b/docs/class-diagram.png differ
diff --git a/docs/dev.org b/docs/dev.org
index dd74995..528248f 100644
--- a/docs/dev.org
+++ b/docs/dev.org
@@ -10,15 +10,16 @@
 Exchange <|--- Binance
 Market <--- "-currencies 2" Currency
 Exchange *--- " #markets 1..*" Market 
-Trader <--- " #exchanges 1..*" Exchange
+Exchange <... Trader
 TradeTracker *--- "-exchanges 1...*" Exchange
-TradeTracker *--- "-traders 0..*" Trader
+TradeTracker "-tracker 1" *--- "-traders 0..*" Trader
 Market <... TradeTracker 
 Market <... Trader
 
 class TradeTracker << (S,#FF7700) Singleton >> {
    -round()
    +start()
+   +getExchange(name: String): Exchange
 }
 
 abstract class Trader {
@@ -67,6 +68,7 @@ class Currency {
   +getName() : String
   +getSymbol() : String
 }
+
 @enduml
 #+END_SRC