Figure 13 There are four structures composed of P, O and H.
The first structure goes across the top of the figure. It is a long line of alternating Ps and Os, connected by alternating single and then dashed lines. Above each P is a double vertical line to an O, while below and to one side of each P is an 'O H', so each P is tetrahedral.
In more details, starting from the left, a line goes down and to the right to an O, then a dashed line goes up and to the right to a P. From here a triangular wedge spreads down and to the left to 'H O', while a double line goes vertically up to an O. From the P a line goes down and to the right to an O, then up and to the right to another P. From here a triangular wedge spreads down and to the right to 'O H', while a double line goes vertically up to an O. From the P a dashed line goes down and to the right to an O, then up and to the right to another P. From here a triangular wedge spreads down and to the left to 'H O', while a double line goes vertically up to an O. From the P a line goes down and to the right to an O, then up and to the right to another P. From here a triangular wedge spreads down and to the right to 'O H', while a double line goes vertically up to an O. From the P a dashed line goes down and to the right to an O, then up and to the right to another P. From the P a dashed line goes down and to the right to an O, then up and to the right to another P. From here a triangular wedge spreads down and to the left to 'H O', while a double line goes vertically up to an O. From the P a line goes down and to the right to an O, then up and to the right.
The second structure, on the left of the figure, is a ring of three Ps, with an O between adjacent Ps. Above each P is a double vertical line going to an O, while sticking out from each P is an OH, so each P is tetrahedral. In more detail, starting at the rear left, there is a P. A dashed line goes down and to the left to an 'H O', while a double vertical line goes up to an O. From the P a line goes down and to the right to an O, then a dashed line goes up and to the right to another P. From the P a line goes down and to the right to an 'O H' while a double line goes up to an O. From the P a triangular wedge spreads down and to the left to an O, then a line goes up and to the left to another P. From the P a triangular wedge spreads down and to the left to an 'H O' while a double line goes up to an O. From the P a dashed line goes down and left to an O, then a triangular wedge points up and to the right to the first P described.
The third structure, on the right of the figure, is a small structure within brackets and labelled 'repeat unit'. At the centre is a P. From the P a double line goes vertically up to an O, while a triangular wedge spreads down and to the left to an O, from where a line goes down and left to an H. From the P, a dashed line goes down and left to an O, from where a triangular wedge spreads up and left to the left bracket. Also from the P a line goes down and to the right to an O, then up and to the right to the right bracket.
The final structure, at the bottom of the figure, is a ring of four Ps, with an O between adjacent Ps. Above each P is a double vertical line going to an O, while sticking out from each P is an OH so each P is tetrahedral. In more detail starting at the rear left, there is a P. A dashed line goes down and to the left to an 'H O', while a double vertical line goes up to an O. From the P a line goes down and to the right to an O, then up and to the right to another P. From the P a dashed line goes down and to the right to an 'O H' while a double line goes up to an O. From the P a triangular wedge spreads down and right to an O, then a dashed line goes up and left to another P. From the P a triangular wedge spreads down and right to an 'O H' while a double line goes up to an O. From the P a line goes down and left to an O, then up and left to another P. From here a triangular wedge spreads down and left to an 'H O' while a double line goes up to an O. From the P a dashed line goes down and left to an O, then a triangular wedge points up and right to the first P described.