[en] Radioactive decays of neutron-deficient isotopes ¹⁵⁶Er (Tsub(1/2)=19.5 min), ¹⁵⁸Er (Tsub(1/2)=2.24 h) and ¹⁶⁰Er (Tsub(1/2)=30 h) have been investigated. Gamma-radiation has been measured by means of spectrometers with Ge (Li) detectors. Internal conversion electron spectra have been measured by means of iron-free beta-spectrometer with toroidal magnetic field and beta-spectrograph with constant homogeneous magnetic field. To confirm schemes of the studied isotope decay the measurements of e-γ-coincidences have been performed at the installation created on the base of a beta- spectrometer with toroidal magnetic field and gamma-spectrometer with Ge(Li) detector. Mass differences ΔM(¹⁵⁶Er→¹⁵⁶Ho)=1670-L-₅₅⁺¹⁰⁵ keV, ΔM(¹⁵⁸Er→¹⁵⁸Ho)=1706-L-₃₅⁺⁵⁵ keV and ΔM(¹⁶⁰Er→¹⁶⁰Ho)=370-L-₉₀⁺¹⁹⁰ keV have been defined. First forbidden beta-transitions of the type 0⁺→1^- have been confidently identified in the decay of ¹⁵⁶Er and ¹⁵⁸Er with anomalously small values lgft=5.2 and 5.4, respectively. One does not observe in the ¹⁵⁸Ho nucleus the population from the ¹⁵⁸Er decay of the level 1⁺, [p523 excitation n523 de-excitation ] expected in accordance with theories. Reliable arguments have been obtained in favour of excitation of the state ¹⁶⁰Ho with I=1⁺ of the above indicated type from ¹⁶⁰Er decay. Using as an example the beta-decay ¹⁵⁶Er→¹⁵⁶Ho there has been demonstrated experimentally there are no delayed beta-transitions which have been expected to occur due to sharp differencies in the nuclei shapes