I am using TEXnicCenter 2.0.2. After compiling the .tex and .bibtex files, all citations are converted in bibitem in the .bbl file. I used the following bibitem in the .tex file:
\bibitem{nadel1990some}
B.~Nadel, \href{https://books.google.tn/books?id=f1evpwAACAAJ}{Some
applications of the constraint satisfaction problem}, no. n°~8 in CSC (Wayne
State University. Department of Computer Science), Wayne State University,
Department of Computer Science, 1990.
\newline\urlprefix\url{https://books.google.tn/books?id=f1evpwAACAAJ}
but I have this error in the first and the last line of the bibitem:
undefined control sequence
Can you help me please