• [1]

    N. D. Birrell and P. C. W. Davies, Quantum Fields in Curved Space (Cambridge University Press, Cambridge 1982)

  • [2]

    O. Nachtmann, Commun. Math. Phys. 6, 1 (1967)

  • [3]

    N. A. Chernikov and E. A. Tagirov, Ann. Inst. Henri Poincaré (A) Physique théorique 9, 109 (1968)

  • [4]

    G. Börner and H. P. Dürr, Il Nuovo Cimento A, Series 10(64), 669 (1969)

  • [5]

    E. A. Tagirov, Ann. of Phys. 76, 561 (1973)

  • [6]

    I. I. Cotăescu, C. Crucean, and A. Pop, Int. J. Mod. Phys. A 23, 2563 (2008)

  • [7]

    G. Pascu, Mod. Phys. Lett. A 27, 1250124 (2012)

  • [8]

    I. I. Cotăescu, G. Pascu, and F. A. Dragoesc, Mod. Phys. A 28, 1350160 (2013)

  • [9]

    V. S. Otchik, Class. Quant. Grav. 2, 539 (1985)

  • [10]

    A. O. Barut and I. H. Duru, Phys. Rev. D 36, 3705 (1987)

  • [11]

    I. E. Andrushkevich and G. V. Shishkin, Theor. Math. Phys. 70, 204 (1987)

  • [12]

    G. V. Shishkin and V. M. Villalba, J. Math. Phys. 30, 2132 (1989)

  • [13]

    V. M. Villalba and U. Percoco, J. Mafh. Phys. 31, 715 (1989)

  • [14]

    G. V. Shishkin, Class. Quantum Grav. 8, 175 (1991)

  • [15]

    F. Finelli, A. Gruppuso, and G. Venturi, Class. Quantum Grav. 16, 3923 (1999)

  • [16]

    I. I. Cotăescu, Phys. Rev. D 65, 084008 (2002)

  • [17]

    V. V. Klishevich and V. A. Tyumentsev, Class. Quantum Grav. 22, 4263 (2005)

  • [18]

    I. I. Cotăescu, Mod. Phys. Lett. A 22, 1613 (2011)

  • [19]

    A. Higuchi, Class. Quant. Gravity 4, 712 (1987)

  • [20]

    I. I. Cotăescu, Gen. Rel. Grav. 42, 861 (2010)

  • [21]

    T. S. Bunch and P. C. W. Davies, Proc. R. Soc. London 360, 117 (1978)

  • [22]

    I. I. Cotăescu, Eur. Phys. J. C 80, 621 (2020)

  • [23]

    I. I. Cotăescu, Eur. Phys. J. C 79, 696 (2019)

  • [24]

    I. I. Cotăescu, Eur. Phys. J. C 80, 535 (2020)

  • [25]

    I. I. Cotăescu and C. Crucean, Prog. Theor. Phys. 124, 1051 (2010)

  • [26]

    I. I. Cotăescu, J. Phys. A: Math. Gen. 33, 9177 (2000)

  • [27]

    I. I. Cotăescu, Europhys. Lett. 86, 20003 (2009)

  • [28]

    W.-K. Tung, Group Theory in Physics (World Sci., Philadelphia, 1984)

  • [29]

    B. Carter and R. G. McLenaghan, Phys. Rev. D 19, 1093 (1979)

  • [30]

    I. I. Cotăescu, Int. J. Mod. Phys. A 33, 1830007 (2018)

  • [31]

    S. Drell and J. D. Bjorken, Relativistic Quantum Fields (McGraw-Hill Book Co., New York 1965)

  • [32]

    I. I. Cotăescu, Mod. Phys. Lett. A 28, 1350033 (2013)

  • [33]

    L. I. Tsaregorodtsev, Russian Phys. Journal 41, 1028 (1989)

  • [34]

    I. I. Cotăescu, GRG 43, 1639 (2011)

  • [35]

    J. Dixmier, Bull. Soc. Math. France 89, 9 (1961)

  • [36]

    B. Takahashi, Bull. Soc. Math. France 91, 289 (1963)

  • [37]

    J. Bros, J.-P. Gazeau, and U. Moschella, Phys. Rev. Lett. 73, 1746 (1994)

  • [38]

    J.-P. Gazeau and M.V. Takook, J. Math. Phys 41(5920), 5920 (2000)

  • [39]

    P. Bartesaghi, J.-P. Gazeau, U. Moschella et al., Class. Quantum. Grav. 18, 4373 (2001)

  • [40]

    T. Garidi, J.-P. Gazeau, and M. Takook, J. Math.Phys. 44, 3838 (2003)

  • [41]

    K.-H. Lotze, Class. Quant. Grav. 4, 1437 (1987)

  • [42]

    K.-H. Lotze, Class. Quantum Grav. 5, 595 (1988)

  • [43]

    K.-H. Lotze, Nuclear Physics B 312, 673 (1989)

  • [44]

    I. L. Buchbinder, E. S. Fradkin, and D. M. Gitman, Forstchr. Phys. 29, 187 (1981)

  • [45]

    I. L. Buchbinder and L. I. Tsaregorodtsev, Int. J. Mod. Phys A 7, 2055 (1992)

  • [46]

    J. Audretsch and P. Spangehl, Class. Quant. Grav. 2, 733 (1985)

  • [47]

    J. Audretsch and P. Spangehl, Phys. Rev. D 33, 997 (1986)

  • [48]

    I. I. Cotăescu and C. Crucean, Phys. Rev. D 87, 044016 (2013)

  • [49]

    C. Crucean and M.-A. Baloi, Pys. Rev. D 93, 044070 (2016)

  • [50]

    C. Crucean and M.-A. Baloi, Int. J. Mod. Phys. A 32, 1750208 (2017)

  • [51]

    F. W. J. Olver, D. W. Lozier, R. F. Boisvert et al., NIST Handbook of Mathematical Functions (Cambridge University Press, 2010)

  • [52]

    A. Erdely, W.F. Magnus, F. Oberhettinger et al., Higher Transcendental Functions, volume Ⅱ- based, in part, on notes left by Harry Bateman (McGraw-Hill Book Co. 1953)