If you want to query for a large set of posts, but don't need full information for each you can use 'fields' =&gt; 'ids'm see Return Fields Parameter.

In this case, I concur with comment, it might make more sense to simply retrieve adjacent post several times. You'll have to use setup_postdata() and wp_reset_postdata() since get_adjacent_post() doesn't allow you to set post explicitly. Unfortunately that function isn't too friendly to reuse or make use of SQL it generates.

Fetching All Posts (200+) in a Category - Performance Issues?
I want to remove the numbers in the bibliography. For example: 


  FERREIRA, L. P. (Org.). O fonoaudiólogo e a escola. São Paulo: Summus, 1991.


without number. I am trying \bibitem [] {Askey}, but [] appears in the document. Can someone tell me how this is done?

\documentclass{article}
\begin{document} 
Resultados obtidos foram utilizado: Askey (1985),$^{\cite{Askey}}$
\begin{thebibliography}{99} 
   \bibitem [] {Askey} ASKEY, R.; WILSON, J. 
     \emph{Some Basic Hypergeometric Polynomial that Generalize Jacobi Polynomial}. 
      Memoirs of the American Mathematical Society, v. 54, p. 1-55, 1985. 
\end{document} 

