diff --git a/R/ancova.qmd b/R/ancova.qmd
index 95e9b6a9..ec9d34ed 100644
--- a/R/ancova.qmd
+++ b/R/ancova.qmd
@@ -52,7 +52,11 @@ my_formula <- as.formula(post ~ drug + pre)
 
 ## Introduction
 
-In this example, we're looking at [Analysis of Covariance](https://documentation.sas.com/doc/en/pgmsascdc/9.4_3.4/statug/statug_glm_examples04.htm). ANCOVA is typically used to analyse treatment differences, to see examples of prediction models go to the [simple linear regression page](linear-regression.qmd).
+ANOVA is a statistical method used to compare the means of three or more groups to determine if at least one group mean is significantly different from the others. Please see the [anova.qmd](ANOVA%20page) for more information. ANCOVA is an extension to ANOVA.
+
+ANCOVA (Analysis of Covariance) is a statistical method that compares the means of two or more groups while controlling for one or more continuous covariates. By adjusting for these covariates, ANCOVA helps to reduce potential confounding effects, allowing for a clearer assessment of the main treatment effects. It assumes linear relationships between covariates and the dependent variable, along with normality and homogeneity of variances.
+
+We follow the example from link [Analysis of Covariance](https://documentation.sas.com/doc/en/pgmsascdc/9.4_3.4/statug/statug_glm_examples04.htm)
 
 ## Data Summary
 
diff --git a/SAS/anova.qmd b/SAS/anova.qmd
index 5863ebf4..8387a2af 100644
--- a/SAS/anova.qmd
+++ b/SAS/anova.qmd
@@ -1,5 +1,5 @@
 ---
-title: "linear-models"
+title: "ANOVA"
 ---
 
 ### **Getting Started**
@@ -60,3 +60,5 @@ knitr::include_graphics("../images/linear/sas-ss-type-3.png")
 ```{r, echo=FALSE, fig.align='center', out.width="75%"}
 knitr::include_graphics("../images/linear/sas-ss-type-4.png")
 ```
+
+Reference: [Sum of squares type I, II, and III](http://dwoll.de/rexrepos/posts/anovaSStypes.html)
diff --git a/SAS/summary_skew_kurt.qmd b/SAS/summary_skew_kurt.qmd
index 5b1722cb..ff48cb18 100644
--- a/SAS/summary_skew_kurt.qmd
+++ b/SAS/summary_skew_kurt.qmd
@@ -48,7 +48,7 @@ The following shows the SAS documentation for the two measures.
 
 ### Skewness
 
-The SAS documentation for Skewness is provided here for convenience:
+The [SAS documentation for Skewness](https://documentation.sas.com/doc/en/vdmmlcdc/8.1/casfedsql/p04x27b92gon3gn10e5y5ybxbvmi.htm) is provided here for convenience:
 ```{r, echo=FALSE, fig.align='center', out.width="100%"}
 knitr::include_graphics("../images/summarystats/sas_skewness.png")
 ```
diff --git a/renv.lock b/renv.lock
index 9b9b35c9..333ec675 100644
--- a/renv.lock
+++ b/renv.lock
@@ -4650,4 +4650,4 @@
       "Hash": "5c715954112b45499fb1dadc6ee6ee3e"
     }
   }
-}
+}
\ No newline at end of file
diff --git a/requirements.txt b/requirements.txt
index 656c3c4f..3c19a102 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -123,4 +123,4 @@ webencodings==0.5.1
 websocket-client==1.7.0
 wheel==0.44.0
 widgetsnbextension==4.0.10
-zipp==3.18.1
+zipp==3.18.1
\ No newline at end of file