[Tex/LaTex] Springer bibliography issue – spbasic

bibtexnatbib

I am using Springer's template svjour3.cls. Since it can be easy to obtain package, for example here I am getting directly to the problem. I have the following MWE, some part comes from directly template

\documentclass[smallextended,natbib]{svjour3} 
%\usepackage[round]{natbib}
%\usepackage[numbers]{natbib}
\begin{document}
 Unlike \cite{harsanyi73}
\bibliographystyle{spbasic}
\bibliography{bibch1}
\end{document}

The problem is that according to manual I need to write natbib in \documentclass[smallextended,natbib]{svjour3}, however, I am getting the error Package natbib Error: Bibliography not compatible with author-year citations. Also error is \providecommand\NAT@force@numbers{}\NAT@force@numbers. I added natbib as usual i.e. \usepackage[round]{natbib} and I got the same error. However, it works fine if I change round to numbers. I have already checked this question or this one, but I couldn't find a solution to my problem. Thanks for any help in advance!

Edit: Here is an example of bibliography

  @article{harsanyi73,
   author = {Harsanyi, John C.},
   title = {Games with Randomly Disturbed Payoffs: A New Rationale for Mixed-Strategy     Equilibrium Points},
    year = {1973},
 journal = {International Journal of Game Theory},
  volume = {2},
  pages = {1--23},
  }

Best Answer

It should have been stated in the User Guide, but spbasic.bst contains the following:

For Springer medical, life sciences, chemistry, geology, engineering and computer science publications. For use with the natbib package (see below). Default is author-year citations. When citations are numbered, please use \usepackage[numbers]{natbib}. A lack of punctuation is the key feature.

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