@article{10.30755/NSJOM.12136,
     author = {Mancho Manev and Veselina Tavkova},
     title = {Hyperspheres in {Euclidean} and {Minkowski} 4-spaces
as almost paracontact almost paracomplex {Riemannian} manifolds},
     journal = {Novi Sad Journal of Mathematics},
     pages = {175 - 185},
     publisher = {mathdoc},
     volume = {51},
     number = {2},
     year = {2021},
     doi = {10.30755/NSJOM.12136},
     url = {http://geodesic.mathdoc.fr/articles/10.30755/NSJOM.12136/}
}