diff --git a/Cargo.toml b/Cargo.toml
index 88a657e..34756f3 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "traquer"
-version = "0.6.1"
+version = "0.7.0"
 edition = "2021"
 description = "technical analysis library"
 license = "Apache-2.0"
diff --git a/src/volume.rs b/src/volume.rs
index 33b4673..26a9cda 100644
--- a/src/volume.rs
+++ b/src/volume.rs
@@ -41,7 +41,7 @@ fn vforce<'a, T: ToPrimitive, U: ToPrimitive>(
                 state.5 + dm
             };
             *state = (h, l, c, trend, cm, dm);
-            Some(v * (1. - (dm / cm)) * trend * 200.0)
+            Some(v * ((dm / cm) - 1.0) * trend * 200.0)
         },
     )
 }
@@ -88,7 +88,6 @@ fn vforce_alt<'a, T: ToPrimitive, U: ToPrimitive>(
 /// ## Sources
 ///
 /// [[1]](https://www.investopedia.com/terms/k/klingeroscillator.asp)
-/// [[2]](https://www.daytrading.com/klinger-volume-oscillator)
 ///
 /// # Examples
 ///
diff --git a/tests/volume_test.rs b/tests/volume_test.rs
index c774175..ab17222 100644
--- a/tests/volume_test.rs
+++ b/tests/volume_test.rs
@@ -49,24 +49,24 @@ fn test_kvo() {
     assert_eq!(stats.close.len(), result.len());
     assert_eq!(
         vec![
-            47653124.52312139,
-            38871537.60795313,
-            56551756.57617685,
-            80719127.50187302,
-            91381485.15827936,
-            102487748.59386584,
-            103133145.86686252,
-            76544074.74621749,
-            76362373.25709169,
-            84632468.62962747,
-            54766782.00020293,
-            53496835.81130403,
-            60063221.578486785,
-            36156452.68826012,
-            39470196.1311378,
-            81568025.19964269,
-            163166676.59742773,
-            90486708.71792603
+            -47653124.52312139,
+            -38871537.60795313,
+            -56551756.57617685,
+            -80719127.50187302,
+            -91381485.15827936,
+            -102487748.59386584,
+            -103133145.86686252,
+            -76544074.74621749,
+            -76362373.25709169,
+            -84632468.62962747,
+            -54766782.00020293,
+            -53496835.81130403,
+            -60063221.578486785,
+            -36156452.68826012,
+            -39470196.1311378,
+            -81568025.19964269,
+            -163166676.59742773,
+            -90486708.71792603
         ],
         result[16..]
     );