diff --git a/pyproject.toml b/pyproject.toml
index b1454bc..3353df7 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -37,7 +37,7 @@ zip-safe = false
 
 [tool.setuptools.dynamic]
 dependencies = { file = ["requirements.txt"] }
-readme = { file = ["README.md"], content-type = "text/markdown" }
+readme = { file = "README.md", content-type = "text/markdown" }
 
 # extra requirements: `pip install pysolid[docs]` or `pip install .[docs,test]`
 # note: the [docs] syntax requires setuptools>=64.0, thus, not working yet.
diff --git a/tests/grid.py b/tests/grid.py
index f6e6f1b..35e92c9 100755
--- a/tests/grid.py
+++ b/tests/grid.py
@@ -7,6 +7,8 @@
 import sys
 import datetime as dt
 
+import numpy as np
+
 import pysolid
 
 
@@ -27,11 +29,42 @@
         'Y_STEP'  : -0.000833333,
     }
 
+    # reference
+    # calculated based on version 0.3.2.post6 on Jun 24, 2024
+    # env: macOS with python-3.10, numpy-1.24
+    # install: manual compilation via f2py
+    tide_e_80_100 = np.array(
+        [[0.01628786, 0.01630887, 0.01633078, 0.01635247, 0.01637394],
+         [0.01633248, 0.01635348, 0.01637538, 0.01639706, 0.01641851],
+         [0.01638009, 0.01640107, 0.01642296, 0.01644462, 0.01646606],
+         [0.01642767, 0.01644864, 0.01647052, 0.01649217, 0.01651359],
+         [0.01647523, 0.01649619, 0.01651805, 0.01653968, 0.01656109]],
+    )
+    tide_n_80_100 = np.array(
+        [[-0.02406203, -0.02412341, -0.02418807, -0.02425273, -0.0243174 ],
+         [-0.02407558, -0.02413699, -0.02420168, -0.02426637, -0.02433107],
+         [-0.02408992, -0.02415136, -0.02421608, -0.02428081, -0.02434554],
+         [-0.02410413, -0.0241656 , -0.02423036, -0.02429511, -0.02435988],
+         [-0.02411821, -0.02417972, -0.0242445 , -0.02430929, -0.02437408]],
+    )
+    tide_u_80_100 = np.array(
+        [[-0.05548462, -0.05533455, -0.05517631, -0.05501789, -0.05485928],
+         [-0.05529561, -0.0551451 , -0.05498639, -0.0548275 , -0.05466843],
+         [-0.05509374, -0.05494276, -0.05478355, -0.05462417, -0.05446461],
+         [-0.05489176, -0.05474031, -0.05458061, -0.05442073, -0.05426067],
+         [-0.05468968, -0.05453776, -0.05437757, -0.05421719, -0.05405664]],
+    )
+
     # calculate
     (tide_e,
      tide_n,
      tide_u) = pysolid.calc_solid_earth_tides_grid(dt_obj, atr, verbose=True)
 
+    # compare
+    assert np.allclose(tide_e[::80, ::100], tide_e_80_100)
+    assert np.allclose(tide_n[::80, ::100], tide_n_80_100)
+    assert np.allclose(tide_u[::80, ::100], tide_u_80_100)
+
     # plot
     out_dir = os.path.abspath(os.path.join(os.path.dirname(__file__), 'pic'))
     os.makedirs(out_dir, exist_ok=True)
diff --git a/tests/point.py b/tests/point.py
index 231b716..d17686d 100755
--- a/tests/point.py
+++ b/tests/point.py
@@ -7,6 +7,8 @@
 import sys
 import datetime as dt
 
+import numpy as np
+
 import pysolid
 
 
@@ -18,8 +20,37 @@
 
     # prepare inputs
     lat, lon = 34.0, -118.0     # Los Angles, CA
-    dt_obj0 = dt.datetime(2020, 11,  1, 4, 0, 0)
-    dt_obj1 = dt.datetime(2020, 12, 31, 2, 0, 0)
+    dt_obj0 = dt.datetime(2020, 11,  5, 12, 0, 0)
+    dt_obj1 = dt.datetime(2020, 12, 31,  0, 0, 0)
+
+    # reference
+    # calculated based on version 0.3.2.post6 on Jun 24, 2024
+    # env: macOS with python-3.10, numpy-1.24
+    # install: manual compilation via f2py
+    dt_out_8000 = np.array(
+        [dt.datetime(2020, 11,  5, 12,  0),
+         dt.datetime(2020, 11, 11,  1, 20),
+         dt.datetime(2020, 11, 16, 14, 40),
+         dt.datetime(2020, 11, 22,  4,  0),
+         dt.datetime(2020, 11, 27, 17, 20),
+         dt.datetime(2020, 12,  3,  6, 40),
+         dt.datetime(2020, 12,  8, 20,  0),
+         dt.datetime(2020, 12, 14,  9, 20),
+         dt.datetime(2020, 12, 19, 22, 40),
+         dt.datetime(2020, 12, 25, 12,  0)], dtype=object,
+    )
+    tide_e_8000 = np.array(
+        [-0.02975027,  0.04146837, -0.02690945, -0.00019223,  0.01624152,
+          0.0532655 , -0.02140918, -0.05554432,  0.01371739, -0.00516968],
+    )
+    tide_n_8000 = np.array(
+        [-0.01275229, -0.02834036,  0.00886857, -0.03247227, -0.05237735,
+         -0.00590791, -0.01990448, -0.01964124, -0.04439581, -0.00410378],
+    )
+    tide_u_8000 = np.array(
+        [ 0.16008235, -0.05721991, -0.15654693, -0.00041214,  0.03041098,
+          0.13082217, -0.1006462 ,  0.24870719, -0.02648802, -0.08420228],
+    )
 
     # calculate
     (dt_out,
@@ -27,6 +58,12 @@
      tide_n,
      tide_u) = pysolid.calc_solid_earth_tides_point(lat, lon, dt_obj0, dt_obj1, verbose=False)
 
+    # compare
+    assert all(dt_out[::8000] == dt_out_8000)
+    assert np.allclose(tide_e[::8000], tide_e_8000)
+    assert np.allclose(tide_n[::8000], tide_n_8000)
+    assert np.allclose(tide_u[::8000], tide_u_8000)
+
     # plot
     out_dir = os.path.abspath(os.path.join(os.path.dirname(__file__), 'pic'))
     os.makedirs(out_dir, exist_ok=True)