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Figure 7
Any lattice [\Lambda\subset\mathbb{R}^{2}] has an obtuse superbase of basis vectors [{\bf v}_1,{\bf v}_2] with [{\bf v}_0 = -{\bf v}_1-{\bf v}_2] and [{\bf v}_{i}\cdot{\bf v}_{j}\leq 0] for distinct [i,j\in\{0,1,2\}], which is unique under isometry, but not under rigid motion (for the rectangular lattice on the right).

IUCrJ
Volume 11| Part 4| July 2024| Pages 453-463
ISSN: 2052-2525
https://doi.org/10.1107/S2052252524004056