XPath: Get parent node from child node

I need get the parent node for child node title 50

At the moment I am using only

//*[title="50"]

How could I get its parent?
Result should be the store node.

<?xml version="1.0" encoding="utf-8"?>
<d:data xmlns:d="defiant-namespace" d:mi="23">
    <store d:mi="22">
        <book price="12.99" d:price="Number" d:mi="4">
            <title d:constr="String" d:mi="1">Sword of Honour</title>
            <category d:constr="String" d:mi="2">fiction</category>
            <author d:constr="String" d:mi="3">Evelyn Waugh</author>
        </book>
        <book price="8.99" d:price="Number" d:mi="9">
            <title d:constr="String" d:mi="5">Moby Dick</title>
            <category d:constr="String" d:mi="6">fiction</category>
            <author d:constr="String" d:mi="7">Herman Melville</author>
            <isbn d:constr="String" d:mi="8">0-553-21311-3</isbn>
        </book>
        <book price="8.95" d:price="Number" d:mi="13">
            <title d:constr="String" d:mi="10">50</title>
            <category d:constr="String" d:mi="11">reference</category>
            <author d:constr="String" d:mi="12">Nigel Rees</author>
        </book>
        <book price="22.99" d:price="Number" d:mi="18">
            <title d:constr="String" d:mi="14">The Lord of the Rings</title>
            <category d:constr="String" d:mi="15">fiction</category>
            <author d:constr="String" d:mi="16">J. R. R. Tolkien</author>
            <isbn d:constr="String" d:mi="17">0-395-19395-8</isbn>
        </book>
        <bicycle price="19.95" d:price="Number" d:mi="21">
            <brand d:constr="String" d:mi="19">Cannondale</brand>
            <color d:constr="String" d:mi="20">red</color>
        </bicycle>
    </store>
</d:data>