Heppke, G., Kitzerow, H.-S., Lötzsch, D., &; Papenfuß, Ch. (1990). Blue phase mixtures exhibiting low fractions of a chiral compound experimental observation of some unusual properties. Liquid Crystals, 8(3), 407–418.https://doi.org/10.1080/02678299008047356 
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DOI: 10.1080/02678299008047356

Noé, R., ZAH, C., MAEDA, M., CANEAU, C., MENOCAL, S., WAGNER, R., &; LEE, T. (1990). OPTICAL AMPLIFIER WITH 27-DB DYNAMIC-RANGE IN A COHERENT TRANSMISSION-SYSTEM. IEEE PHOTONICS TECHNOLOGY LETTERS, 2(2), 120–121.https://doi.org/10.1109/68.47067 
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DOI: 10.1109/68.47067

Noé, R., ZAH, C., MAEDA, M., CANEAU, C., MENOCAL, S., WAGNER, R., &; LEE, T. (1990). OPTICAL AMPLIFIER WITH 27-DB DYNAMIC-RANGE IN A COHERENT TRANSMISSION-SYSTEM. IEEE PHOTONICS TECHNOLOGY LETTERS, 2(2), 120–121.https://doi.org/10.1109/68.47067 
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DOI: 10.1109/68.47067

Noé, R., RODLER, H., GAUKEL, G., EBBERG, A., &; AURACHER, F. (1990). POLARIZATION-INDEPENDENT AND PATTERN-INDEPENDENT OPTICAL FSK HETERODYNE SYSTEM USING DATA-INDUCED POLARIZATION SWITCHING. ELECTRONICS LETTERS, 26(3), 176–177.https://doi.org/10.1049/el:19900119 
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DOI: 10.1049/el:19900119

Noé, R., RODLER, H., GAUKEL, G., NOLL, B., &; EBBERG, A. (1990). HIGH-PERFORMANCE, 2-CHANNEL OPTICAL FSK HETERODYNE SYSTEM WITH POLARIZATION DIVERSITY RECEIVER. ELECTRONICS LETTERS, 26(15), 1109–1110.https://doi.org/10.1049/el:19900717 
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DOI: 10.1049/el:19900717

Kitzerow, H.-S., Crooker, P. P., Kwok, S. L., Xu, J., &; Heppke, G. (1990). Dynamics of blue-phase selective reflections in an electric field. Physical Review A, 42(6), 3442–3448.https://doi.org/10.1103/physreva.42.3442 
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DOI: 10.1103/physreva.42.3442

Kitzerow, H.-S., Crooker, P. P., Kwok, S. L., &; Heppke, G. (1990). A blue phase with negative dielectric anisotropy in an electric field. Statics and dynamics. Journal de Physique, 51(12), 1303–1312.https://doi.org/10.1051/jphys:0199000510120130300 
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Kitzerow, H.-S., Heppke, G., Schmid, H., Jérôme, B., &; Pieranski, P. (1990). First optical observation of Kossel diagrams in chiral smectic phases. Journal de Physique, 51(18), 2087–2099.https://doi.org/10.1051/jphys:0199000510180208700 
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DOI: 10.1051/jphys:0199000510180208700

Schroeter-Wittke, H. (1990). Im Advent kommt Gott uns entgegen. Anmerkungen und Anregungen für Verkündigung und Liturgie in der Vorweihnachtszeit. Zeitschrift Für Gottesdienst Und Predigt, 8(6), 7–13.
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Schroeter-Wittke, H., Schröer, H., &; Bethge, E. (1990). Erben sind wir auf jeden Fall. Über Forschung, Vermittlung und Gedenken. Ein Interview mit Eberhard Bethge . Der Evangelische Erzieher, 42, 453–463.
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Hilgert, J. (1990). Applications of Lie Semigroups in Analysis. In K. H. Hofmann &; et al. (Eds.), The Analytical and Topological Theory of Semigroups. De Gruyter.
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Hilgert, J., &; Hofmann, K. H. (1990). On the Causal Structure of Homogeneous Manifolds. Math. Scand., 67, 119–144.
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