bibliography not compiling correctly

Question

For some reason only one of my bibliography references is compiling properly. The others are not appearing in the reference list at all and do not appear correctly when I type '\cite{source}'. I have one book source (compiling correctly) and the rest are article sources (none compiling correctly). I have looked extensively at the documentation for the article in bibtex but I cannot see that I am missing anything.

\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage[backend=biber, style=alphabetic, natbib]{biblatex}
\addbibresource{ref.bib}
\title{My dissertation}
\author{My name}
\date{May 2021}
\begin{document}
\maketitle
\cite{ostrovskii}
\cite{frankl}
\cite{erdos}
\printbibliography
\end{document}

%% Below is the reference list page (sample) entitled ref.bib

@BOOK{ostrovskii,
        AUTHOR = "
Ostrovskii, Mikhail",
        TITLE = "
Metric Eembeddings : Bilipschitz and coarse embeddings into Banach Spaces",
        PUBLISHER = {Berlin: De Gruyter},
        YEAR = 2013}
@article{frankl,
    AUTHOR =       "Frankl, N., Kupavskii, A., Swanepoel, K. ",
    TITLE =        "Embedding graphs in Euclidean space",
    JOURNAL =      "Journal of Combinatorial Theory, Series A",
    YEAR =         2020,
    VOLUME =       "171",
    DOI =          "https://doi.org/10.1016/j.jcta.2019.105146"
}
@article{erdos,
    author =       "Erdős, P.; Harary, F.; Tutte, W. T. ",
    title =        "On the dimension of a graph",
    journal =      "Mathematika",
    year =         1965,
    volume =       "12",
    number = "2",
    pages = "118-122",
    DOI =          " doi:10.1112/s0025579300005222"
}