Latex warning: citation "*****" on page y undefined on input line*

1 Issues an error

LaTeX Warning: Citation “*****” on page y undefined on input line *

Although you can successfully compile a PDF But the real reference will not appear completely

2 The cause of the problem

When we are using LaTeX When composing a paper , because .tex Source file If the compilation times are not enough, various errors will appear , Now let's analyze Catalog 、 Cross reference 、 reference What are the reasons for the compilation process and errors .

in the light of chart ？？、 surface ？？、 as well as References [??], Such problems are often caused by insufficient compilation times of source files .

2.1 Catalog chart compilation process

When used in the source document \tableofcontents Command build directory ,\ref、\eqref 、\cref When command layout chart formula is cross referenced , Need to be right .tex Source file Compile more than twice . The compilation steps are as follows ：

xelatex demo
xelatex demo

2.2 bibtex Typesetting references

When bibtex When typesetting references , You need to compile it four times for the following steps ：

• Step1: First compilation , use xelatex Wait for the command to compile .tex Source file Generate .aux Supporting documents ;

• Step2: Second compilation , use bibtex Command processing .aux Supporting documents Format of references recorded 、 Reference entry , meanwhile , With the .tex file Under the same file level .bib Literature database as well as .bst Document style Generated after processing .bbl Literature list , The content is thebibliography Environmental Science ;

• Step3: The third compilation ,xelatex Compile and read again .bbl Literature list Generate unreferenced PDF;

• Step4: Fourth compilation ,xelatex Read in .aux Supporting documents Generate the final PDF.

xelatex demo
bibtex  demo
xelatex demo
xelatex demo

2.3 biblatex Typesetting references

When using biblatex When typesetting references , The steps of compiling four times are as follows ：

Step1: xelatex Wait for the command to compile .tex Source file Generate .aux Supporting documents and .bcf References ;

Step2: biber Command processing .bcf References Format of reference documents for records 、 Reference items and other information , Generate .bbl Literature list ,biblatex Macro package recognition uses the information in it to output reference labels and literature tables ;

Step3:xelatex Wait for the command to .tex Source file Compile again , Read in .bbl Literature list , combination .aux Supporting documents Generate correct quotation and description table ;

Step4: If you need backlinks , You need to in biblatex Macro package setting options backref, Reuse xelatex compile , Generate backlinks with literature PDF.

xelatex demo
biber demo
xelatex demo
xelatex demo

The analysis shows chart ？？ Wait for the mistake , It's because of staying Step3 Stage , At this time PDF by Not quoted PDF.

3 Problem solving

It will be easier to solve the problem after understanding the cause of the problem

When setting the compilation chain for compilation

Use pdflatex compile
Then use bibtex compile
And then in use pdflatex Compile twice

perhaps

Use xelatex compile
Then use bibtex compile
And then in use xelatex Compile twice

（ How to set the compilation chain can refer to the following blog ）

VSCODE install LATEX Environmental Science , Parameter configuration , Common problem solving _ Dull like dull blog -CSDN Blog

The successful results are as follows

4 reference

LaTeX Why should source files be compiled multiple times - LaTeX Studio Question answering community

latex Build process _ Fan Xiaohua's column -CSDN Blog

(11 Bar message ) 【 Error summary 】LaTex Warning: citation undefined_ Programming stack -CSDN Blog