using System;
using System.IO;
using System.Text.RegularExpressions;
 
public class Test
{
	public static void Main()
	{
		var line = "@article{Gettys90,\n   author = {Jim Gettys and Phil Karlton and Scott McGregor},\n   abstract = {A technical overview of the X11 functionality. This is an update of the X10 TOG paper by Scheifler & Gettys.},\n   journal = {Software Practice and Experience},\n   volume = {20},\n   number = {S2},\n   title = {The {X} Window System, Version 11},\n   year = {1990}\n\n},\n\n\n@article{Gettys90,\n   author = {Jim Gettys and Phil Karlton and Scott McGregor},\n   abstract = {A technical overview of the X11 functionality. This is an update of the X10 TOG paper by Scheifler & Gettys.},\n   journal = {Software Practice and Experience},\n   volume = {20},\n   number = {S2},\n   title = {The {X} Window System, Version 11},\n   year = {1990}\n},\n@article{Gettys90,\n   author = {Jim Gettys and Phil Karlton and Scott McGregor},\n   abstract = {A technical overview of the X11 functionality. This is an update of the X10 TOG paper by Scheifler & Gettys.},\n\n  journal = {Software Practice and Experience},\n\n  volume = {20},\n   number = {S2},\n   title = {The {X} Window System, Version 11},\n   year = {1990}\n}";
        var kvp = @"(?<kvp>\W*([a-zA-Z]+) = {(.+?)},)";
        var pattern = string.Format("(?<entry>@(\\w+)\\{{(\\w+),{0}{0}*(\\W*([a-zA-Z]+) = \\{{(.+?)}})\\W*}},?\\s*)+", kvp);
        // No need to recurse (?<entry>) because we can just use `+` quantifier
        var matches = Regex.Matches(line, pattern);
            foreach (Match m in matches)
               Console.WriteLine(m.Groups["kvp"].Value);
 
	}
}

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