Own work -- Converted from the following vector PostScript source code:

%! 306 396 translate .925 dup scale 1 setlinejoin 28 setlinewidth /x 2812.5 sqrt def/y 3528 sqrt 200 add def .9 .1 .2 setrgbcolor /A{gsave 48 setlinewidth .6 setgray stroke grestore stroke}def y 42 add neg dup moveto y 42 add neg x 2 mul y 42 add sub lineto -100 -100 75 135 225 arcn -200 x sub 648 sqrt add x neg 18 225 135 arcn 0 y 42 -45 90 arc 0 0 y 42 add 90 270 arc 0 y neg 42 -90 45 arc -200 x sub 648 sqrt add x 18 225 135 arcn -100 100 75 135 225 arcn y 42 add neg y 42 add x 2 mul sub lineto y 42 add neg dup neg lineto A y 42 add dup neg moveto y 42 add x 2 mul y 42 add sub lineto 100 -100 75 45 315 arc 200 x add 648 sqrt sub x neg 18 315 45 arc 0 y 42 225 90 arcn 0 0 y 42 add 90 -90 arcn 0 y neg 42 270 135 arcn 200 x add 648 sqrt sub x 18 315 45 arc 100 100 75 45 315 arc y 42 add y 42 add x 2 mul sub lineto y 42 add dup lineto A y 42 add neg dup neg moveto -175 y 42 add lineto -100 100 x 2 mul add 75 180 225 arc 100 100 x 2 mul add neg 75 45 0 arcn 175 y 42 add neg lineto y 42 add dup neg lineto A y 42 add neg dup moveto -175 y 42 add neg lineto -100 100 x 2 mul add neg 75 180 135 arcn 100 100 x 2 mul add 75 315 0 arc 175 y 42 add lineto y 42 add dup lineto A 0 setlinejoin 48 setlinewidth .6 setgray -100 -100 75 23 67 arc stroke 100 100 75 203 247 arc stroke -100 100 75 23 67 arc stroke 100 -100 75 203 247 arc stroke -100 100 75 247 225 arcn -17 17 rlineto stroke 100 -100 75 67 45 arcn 17 -17 rlineto stroke -100 -100 75 247 225 arcn -17 17 rlineto stroke 100 100 75 67 45 arcn 17 -17 rlineto stroke 0 0 y 42 add 25 36 arc stroke 0 0 y 42 add 205 216 arc stroke 0 0 y 42 add 119 134 arc stroke 0 0 y 42 add 299 314 arc stroke 0 y neg 42 -10 -90 arcn 0 0 y 42 add 270 258 arcn stroke -117 83 moveto -83 117 lineto stroke 117 -83 moveto 83 -117 lineto stroke 0 200 moveto 17 17 rmoveto -34 -34 rlineto stroke 200 0 moveto 17 17 rmoveto -34 -34 rlineto stroke -200 0 moveto 17 17 rmoveto -34 -34 rlineto stroke 100 x 2 mul add 100 moveto 17 17 rmoveto -34 -34 rlineto stroke 100 x 2 mul add neg 100 moveto 17 17 rmoveto -34 -34 rlineto stroke 100 x 2 mul add -100 moveto 17 17 rmoveto -34 -34 rlineto stroke 100 x 2 mul add neg -100 moveto 17 17 rmoveto -34 -34 rlineto stroke 100 x sub 100 x add moveto -17 17 rmoveto 34 -34 rlineto stroke 100 x add 100 x sub moveto -17 17 rmoveto 34 -34 rlineto stroke -100 x sub -100 x add moveto -17 17 rmoveto 34 -34 rlineto stroke -100 x add -100 x sub moveto -17 17 rmoveto 34 -34 rlineto stroke 100 x 2 mul add neg 100 moveto -31 31 rmoveto -42 42 rlineto stroke 100 x 2 mul add -100 moveto 31 -31 rmoveto 42 -42 rlineto stroke y 42 add dup 75 sub moveto 0 75 rlineto -75 0 rlineto stroke y 42 add neg dup 75 add moveto 0 -75 rlineto 75 0 rlineto stroke y 42 add dup neg 75 add moveto 0 -75 rlineto -75 0 rlineto stroke y 42 add neg dup neg 75 sub moveto 0 75 rlineto 75 0 rlineto stroke 28 setlinewidth .9 .1 .2 setrgbcolor -100 -100 75 22 68 arc stroke 100 100 75 202 248 arc stroke -100 100 75 22 68 arc stroke 100 -100 75 202 248 arc stroke -100 100 75 248 225 arcn -18 18 rlineto stroke 100 -100 75 68 45 arcn 18 -18 rlineto stroke -100 -100 75 248 225 arcn -18 18 rlineto stroke 100 100 75 68 45 arcn 18 -18 rlineto stroke 0 0 y 42 add 24 37 arc stroke 0 0 y 42 add 204 217 arc stroke 0 0 y 42 add 118 135 arc stroke 0 0 y 42 add 298 315 arc stroke 0 y neg 42 -9 -90 arcn 0 0 y 42 add 270 257 arcn stroke -118 82 moveto -82 118 lineto stroke 118 -82 moveto 82 -118 lineto stroke 0 200 moveto 18 18 rmoveto -36 -36 rlineto stroke 200 0 moveto 18 18 rmoveto -36 -36 rlineto stroke -200 0 moveto 18 18 rmoveto -36 -36 rlineto stroke 100 x 2 mul add 100 moveto 18 18 rmoveto -36 -36 rlineto stroke 100 x 2 mul add neg 100 moveto 18 18 rmoveto -36 -36 rlineto stroke 100 x 2 mul add -100 moveto 18 18 rmoveto -36 -36 rlineto stroke 100 x 2 mul add neg -100 moveto 18 18 rmoveto -36 -36 rlineto stroke 100 x sub 100 x add moveto -18 18 rmoveto 36 -36 rlineto stroke 100 x add 100 x sub moveto -18 18 rmoveto 36 -36 rlineto stroke -100 x sub -100 x add moveto -18 18 rmoveto 36 -36 rlineto stroke -100 x add -100 x sub moveto -18 18 rmoveto 36 -36 rlineto stroke 100 x 2 mul add neg 100 moveto -30 30 rmoveto -44 44 rlineto stroke 100 x 2 mul add -100 moveto 30 -30 rmoveto 44 -44 rlineto stroke y 42 add dup 76 sub moveto 0 76 rlineto -76 0 rlineto stroke y 42 add neg dup 76 add moveto 0 -76 rlineto 76 0 rlineto stroke y 42 add dup neg 76 add moveto 0 -76 rlineto -76 0 rlineto stroke y 42 add neg dup neg 76 sub moveto 0 76 rlineto 76 0 rlineto stroke showpage %EOF

 

This vector image includes elements that have been taken or adapted from this file:

 Celtic-knot-insquare-39crossings.svg.