diff --git a/src/rydstate/species/strontium.py b/src/rydstate/species/strontium.py
index dab8436..c20a43f 100644
--- a/src/rydstate/species/strontium.py
+++ b/src/rydstate/species/strontium.py
@@ -35,6 +35,19 @@ class _StrontiumAbstract(SpeciesObject):
     model_potential_parameter_fei_2009 = (0.9959, 16.9567, 0.2648, 0.1439)
 
 
+class Strontium87(_StrontiumAbstract):
+    name = "Sr87"
+    i_c = 9 / 2
+
+    # https://physics.nist.gov/PhysRefData/Handbook/Tables/strontiumtable1.htm
+    _isotope_mass_u = 86.908884  # u
+    _corrected_rydberg_constant = (
+        rydberg_constant.m / (1 + electron_mass.to("u").m / _isotope_mass_u),
+        None,
+        str(rydberg_constant.u),
+    )
+
+
 class Strontium88(_StrontiumAbstract):
     name = "Sr88"
     i_c = 0
@@ -47,9 +60,20 @@ class Strontium88(_StrontiumAbstract):
         str(rydberg_constant.u),
     )
 
-    # -- [1] Phys. Rev. A 108, 022815 (2023)
-    # -- [2] http://dx.doi.org/10.17169/refubium-34581
-    # -- [3] Comput. Phys. Commun. 45, 107814 (2021)
+    # -- [1] Brienza 2023, Phys. Rev. A 108, 022815
+    #        Microwave spectroscopy of low-l singlet strontium Rydberg states at intermediate n
+    #        Isotope Sr84
+    # -- [2] Patsch 2021, http://dx.doi.org/10.17169/refubium-34581
+    #        Dissertation: Control of Rydberg atoms for quantum technologies
+    #        see table A.2 (and A.3)
+    #        Isotope not specified (probably Sr88)
+    # -- [3] Robertson 2021, Comput. Phys. Commun. 45, 107814 (2021)
+    #        ARC 3.0: An expanded Python toolbox for atomic physics calculations
+    #        see table B.1
+    #        Isotope Sr88
+    # -- [4] (not used but also lot of data) Vaillant 2012, J. Phys. B: At. Mol. Opt. Phys. 45 135004
+    #        Long-range Rydberg-Rydberg interactions in calcium, strontium and ytterbium
+
     _quantum_defects: ClassVar = {
         # singlet
         (0, 0.0, 0): (3.2688559, -0.0879, -3.36, 0.0, 0.0),  # [1]
@@ -70,16 +94,3 @@ class Strontium88(_StrontiumAbstract):
         (3, 3.0, 1): (0.119, -2.0, 100, 0.0, 0.0),  # [3]
         (3, 4.0, 1): (0.120, -2.4, 120, 0.0, 0.0),  # [3]
     }
-
-
-class Strontium87(_StrontiumAbstract):
-    name = "Sr87"
-    i_c = 9 / 2
-
-    # https://physics.nist.gov/PhysRefData/Handbook/Tables/strontiumtable1.htm
-    _isotope_mass_u = 86.908884  # u
-    _corrected_rydberg_constant = (
-        rydberg_constant.m / (1 + electron_mass.to("u").m / _isotope_mass_u),
-        None,
-        str(rydberg_constant.u),
-    )
diff --git a/src/rydstate/species/ytterbium.py b/src/rydstate/species/ytterbium.py
index d04d2eb..6c0a37a 100644
--- a/src/rydstate/species/ytterbium.py
+++ b/src/rydstate/species/ytterbium.py
@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 from pathlib import Path
 from typing import ClassVar
 
@@ -60,3 +62,41 @@ class Ytterbium174(_YtterbiumAbstract):
         None,
         str(rydberg_constant.u),
     )
+
+    # -- [1] Peper 2024, http://arxiv.org/abs/2406.01482
+    #        Spectroscopy and modeling of 171Yb Rydberg states for high-fidelity two-qubit gates
+    #        see Table I
+    #        Isotope Yb174
+    # -- [2] Wilson 2019, https://arxiv.org/abs/1912.08754
+    #        Trapped arrays of alkaline earth Rydberg atoms in optical tweezers
+    #        fit only valid from 28s upward
+    #        see Table S2, but adjusted for non-Rydberg Ritz
+    #        Isotope Yb174
+    # -- [3] Kuroda 2025, https://arxiv.org/abs/2507.11487
+    #        Microwave spectroscopy and multi-channel quantum defect analysis of ytterbium Rydberg states
+    #        see Table S1 - S8
+    #        Isotope Yb174
+
+    _quantum_defects: ClassVar = {
+        # singlet
+        (0, 0.0, 0): (4 + 0.355101645, 0.277673956, 0.0, 0.0, 0.0),  # [3] S2
+        (1, 1.0, 0): (3 + 0.922709076, 2.60055203, 0.0, 0.0, 0.0),  # [3] S4
+        (2, 2.0, 0): (2 + 0.729513646, -0.0377841183, 0.0, 0.0, 0.0),  # [3] S6
+        (3, 3.0, 0): (0.276158949, -12.7258012, 0.0, 0.0, 0.0),  # [3] S7
+        # triplet
+        (0, 1.0, 1): (4 + 0.4382, 4, -1e4, 8e6, -3e9),  # [2] S2  # but adjusted for non-Rydberg Ritz
+        (1, 0.0, 1): (3 + 0.953661478, -0.287531374, 0.0, 0.0, 0.0),  # [3] S3
+        (1, 1.0, 1): (3 + 0.982084772, -5.45063476, 0.0, 0.0, 0.0),  # [3] S4
+        (1, 2.0, 1): (3 + 0.925150932, -2.69197178, 66.7159709, 0.0, 0.0),  # [3] S5
+        (2, 1.0, 1): (2 + 0.75258093, 0.3826, -483.1, 0.0, 0.0),  # [1] Table I
+        (2, 2.0, 1): (2 + 0.752292223, 0.104072325, 0.0, 0.0, 0.0),  # [3] S6
+        (2, 3.0, 1): (2 + 0.72902016, -0.705328923, 829.238844, 0.0, 0.0),  # [3] S1
+        (3, 2.0, 1): (0.0718252326, -1.00091963, -106.291066, 0.0, 0.0),  # [3] S1
+        (3, 3.0, 1): (0.0715123712, -0.768462937, 0.0, 0.0, 0.0),  # [3] S7
+        (3, 4.0, 1): (0.0839027969, -2.91009023, 0.0, 0.0, 0.0),  # [3] S1
+        (4, 3.0, 1): (0.0260964574, -0.14139526, 0.0, 0.0, 0.0),  # [3] S1
+        (4, 5.0, 1): (0.02529201, -0.11588052, 0.0, 0.0, 0.0),  # [3] S1  # actually from Yb171
+        #  +/- states
+        # (4, 4.0, "+"): (0.0262659964, 0.0254568575, 0.0, 0.0, 0.0),  # [3] S8
+        # (4, 4.0, "-"): (-0.148808463, -0.134219071, 0.0, 0.0, 0.0),  # [3] S8
+    }