diff --git a/README.md b/README.md
index ffe0bd5..12eea0f 100644
--- a/README.md
+++ b/README.md
@@ -48,7 +48,7 @@ Guidotti E (2022). “calculus: High-Dimensional Numerical and Symbolic Calculus
 A BibTeX entry for LaTeX users is
 
 ```bibtex
-@Article{,
+@Article{calculus,
   title = {{calculus}: High-Dimensional Numerical and Symbolic Calculus in {R}},
   author = {Emanuele Guidotti},
   journal = {Journal of Statistical Software},
diff --git a/vignettes/derivatives.Rmd b/vignettes/derivatives.Rmd
index 7ad5a8f..ab6b090 100644
--- a/vignettes/derivatives.Rmd
+++ b/vignettes/derivatives.Rmd
@@ -111,7 +111,7 @@ Guidotti E (2022). “calculus: High-Dimensional Numerical and Symbolic Calculus
 A BibTeX entry for LaTeX users is
 
 ```bibtex
-@Article{,
+@Article{calculus,
   title = {{calculus}: High-Dimensional Numerical and Symbolic Calculus in {R}},
   author = {Emanuele Guidotti},
   journal = {Journal of Statistical Software},
diff --git a/vignettes/differential-operators.Rmd b/vignettes/differential-operators.Rmd
index e459a7f..299b75d 100644
--- a/vignettes/differential-operators.Rmd
+++ b/vignettes/differential-operators.Rmd
@@ -245,7 +245,7 @@ Guidotti E (2022). “calculus: High-Dimensional Numerical and Symbolic Calculus
 A BibTeX entry for LaTeX users is
 
 ```bibtex
-@Article{,
+@Article{calculus,
   title = {{calculus}: High-Dimensional Numerical and Symbolic Calculus in {R}},
   author = {Emanuele Guidotti},
   journal = {Journal of Statistical Software},
diff --git a/vignettes/einstein.Rmd b/vignettes/einstein.Rmd
index 9b990e4..15f8c80 100644
--- a/vignettes/einstein.Rmd
+++ b/vignettes/einstein.Rmd
@@ -60,7 +60,7 @@ Guidotti E (2022). “calculus: High-Dimensional Numerical and Symbolic Calculus
 A BibTeX entry for LaTeX users is
 
 ```bibtex
-@Article{,
+@Article{calculus,
   title = {{calculus}: High-Dimensional Numerical and Symbolic Calculus in {R}},
   author = {Emanuele Guidotti},
   journal = {Journal of Statistical Software},
diff --git a/vignettes/hermite.Rmd b/vignettes/hermite.Rmd
index b7928ec..4f8352a 100644
--- a/vignettes/hermite.Rmd
+++ b/vignettes/hermite.Rmd
@@ -62,7 +62,7 @@ Guidotti E (2022). “calculus: High-Dimensional Numerical and Symbolic Calculus
 A BibTeX entry for LaTeX users is
 
 ```bibtex
-@Article{,
+@Article{calculus,
   title = {{calculus}: High-Dimensional Numerical and Symbolic Calculus in {R}},
   author = {Emanuele Guidotti},
   journal = {Journal of Statistical Software},
diff --git a/vignettes/integrals.Rmd b/vignettes/integrals.Rmd
index 7dd76f6..12ecd7e 100644
--- a/vignettes/integrals.Rmd
+++ b/vignettes/integrals.Rmd
@@ -105,7 +105,7 @@ Guidotti E (2022). “calculus: High-Dimensional Numerical and Symbolic Calculus
 A BibTeX entry for LaTeX users is
 
 ```bibtex
-@Article{,
+@Article{calculus,
   title = {{calculus}: High-Dimensional Numerical and Symbolic Calculus in {R}},
   author = {Emanuele Guidotti},
   journal = {Journal of Statistical Software},
diff --git a/vignettes/ode.Rmd b/vignettes/ode.Rmd
index 66aebd2..4dfafdb 100644
--- a/vignettes/ode.Rmd
+++ b/vignettes/ode.Rmd
@@ -157,7 +157,7 @@ Guidotti E (2022). “calculus: High-Dimensional Numerical and Symbolic Calculus
 A BibTeX entry for LaTeX users is
 
 ```bibtex
-@Article{,
+@Article{calculus,
   title = {{calculus}: High-Dimensional Numerical and Symbolic Calculus in {R}},
   author = {Emanuele Guidotti},
   journal = {Journal of Statistical Software},
diff --git a/vignettes/taylor.Rmd b/vignettes/taylor.Rmd
index d0fc420..22fe2ce 100644
--- a/vignettes/taylor.Rmd
+++ b/vignettes/taylor.Rmd
@@ -64,7 +64,7 @@ Guidotti E (2022). “calculus: High-Dimensional Numerical and Symbolic Calculus
 A BibTeX entry for LaTeX users is
 
 ```bibtex
-@Article{,
+@Article{calculus,
   title = {{calculus}: High-Dimensional Numerical and Symbolic Calculus in {R}},
   author = {Emanuele Guidotti},
   journal = {Journal of Statistical Software},