diff --git a/models/Market.json b/models/Market.json
index dca15cf..e1a97e8 100644
--- a/models/Market.json
+++ b/models/Market.json
@@ -10,26 +10,21 @@
       "type": "array",
       "description": "The list of goods that are exported from this market.",
       "items": {
-        "type": "object",
-        "properties": {
-          "symbol": {
-            "type": "string",
-            "description": "The symbol of the good."
-          }
-        }
+        "$ref": "./TradeGood.json"
       }
     },
     "imports": {
       "type": "array",
       "description": "The list of goods that are sought as imports in this market.",
       "items": {
-        "type": "object",
-        "properties": {
-          "symbol": {
-            "type": "string",
-            "description": "The symbol of the good."
-          }
-        }
+        "$ref": "./TradeGood.json"
+      }
+    },
+    "exchange": {
+      "type": "array",
+      "description": "The list of goods that are bought and sold between agents at this market.",
+      "items": {
+        "$ref": "./TradeGood.json"
       }
     },
     "transactions": {
@@ -50,6 +45,7 @@
   "required": [
     "symbol",
     "exports",
-    "imports"
+    "imports",
+    "exchange"
   ]
 }
\ No newline at end of file
diff --git a/models/TradeGood.json b/models/TradeGood.json
index e1af4ee..f5bb7ec 100644
--- a/models/TradeGood.json
+++ b/models/TradeGood.json
@@ -1,6 +1,6 @@
 {
   "type": "object",
-  "attributes": {
+  "properties": {
     "symbol": {
       "$ref": "./TradeSymbol.json"
     },
@@ -9,11 +9,11 @@
     },
     "description": {
       "type": "string"
-    },
-    "required": [
-      "symbol",
-      "name",
-      "description"
-    ]
-  }
+    }
+  },
+  "required": [
+    "symbol",
+    "name",
+    "description"
+  ]
 }
\ No newline at end of file