我需要修复参考书目和使用 \cite 的可能性

Question

我有参考书目，但无法使用 \cite[]{key}。它根本不起作用。我只能看到键中的字母（而不是链接）

\begin{thebibliography}{9}
\bibitem{MA} M.Adachi, \emph{Embedding and Immersions}, American Mathematical Society, 1984.
\bibitem{AW} A. Wasserman, \emph{The Atiyah-Singer Index Theorem}, online LENT, 2010.
\bibitem{E} R.Engelking, \emph{Topologia ogólna}, PWN, Warszawa, 2007.
\bibitem{MJ} J.Milnor, \emph{Lectures on the h-cobordism theorem}, Princeton University Press, 1993.
\bibitem{MP} M.Persson, \emph{The Whitney embedding theorem}, UMEA University, 2014.
\bibitem{JL} J.Lawson, \emph{Differential Geometry}, Louisiana State University, 2006, \url{https://www.math.lsu.edu/~lawson/Chapter1.pdf}
\bibitem{MG} M.Gualtieri, \emph{Topology 1, Smooth manifolds}, University of Toronto, 2016, \url{http://www.math.toronto.edu/mgualt/courses/MAT1300F-2016/}
\bibitem{SL} S.Lu, \emph{Isometric Embedding of Riemannian manifolds}, 2012.
\bibitem{MZ} M.Zakrzewski, \emph{Notatki do seminarium dyplomowego}.
\end{thebibliography}

\begin{defn}\label{Rozmaitość topologiczna}\cite{M} - I will see in this particular case: Rozmaitość topologiczna M. This `M` is not a link

Macroses: ```
\documentclass[12pt,a4paper]{mwrep} %do druku dwustronnego proszę dodać twoside
\usepackage{polski}
\usepackage[utf8]{inputenc}
\usepackage{amsmath}
\usepackage{hyperref}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{physics}
\usepackage{amsthm}
\usepackage[shortlabels]{enumitem}
\usepackage[pdftex]{graphicx}
\graphicspath{{jpg/}{png/}}
%\usepackage[margin=2.5cm]{geometry}



% otoczenia dla twierdzeń
\newtheorem{tw}{Twierdzenie}[chapter]
\newtheorem{lem}{Lemat}[chapter]
\newtheorem{wns}[tw]{Wniosek}


% otoczenia dla definicji i przykładów
\theoremstyle{definition}
\newtheorem{przkl}{Przykład}[chapter]
\newtheorem{defn}[tw]{Definicja}

% otoczenie dla uwagi
\theoremstyle{remark}
\newtheorem{uwg}[tw]{Uwaga}


% definicje zbiorów liczbowych
\def\RR{\mathbb{R}}% liczby rzeczywiste
\def\NN{\mathbb{N}}% liczny naturalne
\def\CC{\mathbb{C}}% liczby zespolone
\def\QQ{\mathbb{Q}}% liczny wymierne

%zbiór pusty
\usepackage{amssymb}

\let\oldemptyset\emptyset
\let\emptyset\varnothing


\usepackage[
    backend=biber,
    style=authoryear-icomp,
    sortlocale=pl_PL,
    natbib=true,
    url=false, 
    doi=true,
    eprint=false
]{biblatex}

\begin{document}
\baselineskip18pt
\begin{titlepage}
\begin{center}