Here is my MWE with all the packages in my complete document.

%!PS-Adobe-3.0 EPSF-3.0
%%BoundingBox: 19 19 221 221
%%CreationDate: Mon Sep 29 1997
%%Creator: programmed by hand (JK)
  20 20 moveto
  20 220 lineto
  220 220 lineto
  220 20 lineto
2 setlinewidth
  .4 setgray fill

% \usepackage{amssymb}



This is citation of online web page \cite{online1}. Another online \cite{online2}. Another online \cite{online3}. This is random citation of research papers. \cite{simonyan2014very}. Another paper \cite{he2016deep}

% end of file template.tex

Besides, I am adding the contents of my reference.bib file below.


  author = {Collins Online English Dictionary},
  title = {Language},
  year = {},
  url = {https://www.collinsdictionary.com/dictionary/english/language},
  urldate = {2021-01-08}

  title={Sign Language},
  author = {Wikipedia},
  url = {https://en.wikipedia.org/wiki/Sign_language},
  urldate = {2021-01-08}

  title={What is Sign Language?},
  author = {David M. Perlmutter },
  url = {https://www.linguisticsociety.org/content/what-sign-language},
  urldate = {2021-01-08}

  title={Very deep convolutional networks for large-scale image recognition},
  author={Simonyan, Karen and Zisserman, Andrew},
  journal={arXiv preprint arXiv:1409.1556},

  title={Deep residual learning for image recognition},
  author={He, Kaiming and Zhang, Xiangyu and Ren, Shaoqing and Sun, Jian},
  booktitle={Proceedings of the IEEE conference on computer vision and pattern recognition},

The output looks like that. Notice that, only online references contains (????). I want to remove these question marks. Output

  • 1
    @online entries require a year, which then appears in the parantheses. This may be the year, when the website was set up or something like that. I couldn't reproduce the (????) but instead ended up with () when removing the year = xxxx, line from the bibliography though.
    – Markus G.
    May 18 at 13:47
  • @Markus thanks for your concern but that doesn't solve my full problem. I think the problem lies in the packages. I may need to import or remove some packages but couldn't conclude anything for sure. May 18 at 13:59
  • 1
    However, you do realise that either year or date (but not urldate) is required(!) for @online-type entries? I am referring to this answer: tex.stackexchange.com/a/263912/118712
    – Markus G.
    May 18 at 14:02
  • @MarkusG. no, I didn't know that year or date is mandatory. I think I know how to proceed further with my document. Sometimes little knowledge can solve big problems (or seem to be big). Thanks for the information. May 19 at 5:51

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