diff --git a/DESCRIPTION b/DESCRIPTION
index 0321337..19a32b1 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -9,10 +9,10 @@ Description: Functions to calculate commonly used public health statistics and
     of proportions, crude rates, means, directly standardised rates, indirectly 
     standardised rates and standardised mortality ratios. Statistical methods 
     are referenced in the following publications. 
-    Breslow NE, Day NE (1987) <doi:https://doi.org/10.1002/sim.4780080614>.
-    Dobson et al (1991) <doi:https://doi.org/10.1002/sim.4780100317>. 
-    Armitage P, Berry G (2002) <doi:https://doi.org/10.1002/9780470773666>.
-    Wilson EB. (1927) <doi:https://doi.org/10.1080/01621459.1927.10502953>.
+    Breslow NE, Day NE (1987) <doi:10.1002/sim.4780080614>.
+    Dobson et al (1991) <doi:10.1002/sim.4780100317>. 
+    Armitage P, Berry G (2002) <doi:10.1002/9780470773666>.
+    Wilson EB. (1927) <doi:10.1080/01621459.1927.10502953>.
     Altman DG et al (2000, ISBN: 978-0-727-91375-3).
 Authors@R: c(person("Anderson", "Georgina", , "georgina.anderson@phe.gov.uk", c("aut", "cre")),
              person("Fox", "Sebastian", , "sebastian.fox@phe.gov.uk", c("ctb")),
diff --git a/cran-comments.md b/cran-comments.md
index d28b1d2..1aac495 100644
--- a/cran-comments.md
+++ b/cran-comments.md
@@ -1,8 +1,9 @@
 
 ## Resubmission
-I have amended the description text in the DESCRIPTION file to include doi or 
-ISBN references to the statistical methods used by the package functions. I also made
-the description text more concise.
+I have amended the description text in the DESCRIPTION file to include doi 
+<doi:10.prefix.suffix> or 
+ISBN references to the statistical methods used by the package functions. 
+I also made the description text more concise.
 
 I also updated one of the references cited in the function documentation for 
 the phe_rate, phe_isr and phe_smr functions.