diff --git a/content/zettels/analog_to_digital_converters.md b/content/zettels/analog_to_digital_converters.md
index d4ace06..889d576 100644
--- a/content/zettels/analog_to_digital_converters.md
+++ b/content/zettels/analog_to_digital_converters.md
@@ -14,7 +14,7 @@ Tags
 
 <https://dewesoft.com/daq/types-of-adc-converters>
 
--   Delta Sigma <baker11_how_delta_sigma_adcs_work_part>
+-   Delta Sigma (<a href="#citeproc_bib_item_1">Baker 2011</a>)
 -   Successive Approximation
 
 
@@ -84,7 +84,7 @@ The quantization is:
 
 {{< youtube b9lxtOJj3yU >}}
 
-Also see <kester05_takin>.
+Also see (<a href="#citeproc_bib_item_2">Kester 2005</a>).
 
 
 ## Link between required dynamic range and effective number of bits {#link-between-required-dynamic-range-and-effective-number-of-bits}
@@ -96,12 +96,27 @@ Also see <kester05_takin>.
 
 ## Oversampling {#oversampling}
 
-<lab13_improv_adc>
+(<a href="#citeproc_bib_item_3">Lab 2013</a>)
+
+To have additional \\(w\\) bits of resolution, the oversampling frequency \\(f\_{os}\\) should be:
+
+\begin{equation}
+f\_{os} = 4^w \cdot f\_s
+\end{equation}
+
+
+### When Oversampling and Averaging Will Work {#when-oversampling-and-averaging-will-work}
+
+> Key points to consider are:
+>
+> -   The noise must approximate **white noise** with uniform power spectral density over the frequency band of interest.
+> -   The **noise amplitude must be sufficient** to cause the input signal to change randomly from sample to sample by amounts comparable to at least the distance between two adjacent codes (i.e., 1 LSB).
+> -   The input signal can be represented as a random variable that has equal probability of existing at any value between two adjacent ADC codes.
 
 
 ## Sigma Delta ADC {#sigma-delta-adc}
 
-From <&schmidt20_desig_high_perfor_mechat_third_revis_edition>:
+From (<a href="#citeproc_bib_item_4">Schmidt, Schitter, and Rankers 2020</a>):
 
 > The low cost and excellent linearity properties of the Sigma-Delta ADC have replaced other ADC types in many measurement and registration systems, especially where storage of data is more important than real-time measurement.
 > This has typically been the case in audio recording and reproduction.
@@ -125,4 +140,9 @@ Therefore, even though there are sigma-delta ADC with high precision and samplin
 
 ## Bibliography {#bibliography}
 
-<./biblio/references.bib>
+<style>.csl-entry{text-indent: -1.5em; margin-left: 1.5em;}</style><div class="csl-bib-body">
+  <div class="csl-entry"><a id="citeproc_bib_item_1"></a>Baker, Bonnie. 2011. “How Delta-Sigma Adcs Work, Part.” <i>Analog Applications</i> 7.</div>
+  <div class="csl-entry"><a id="citeproc_bib_item_2"></a>Kester, Walt. 2005. “Taking the Mystery out of the Infamous Formula, $snr = 6.02 N + 1.76 Db$, and Why You Should Care.”</div>
+  <div class="csl-entry"><a id="citeproc_bib_item_3"></a>Lab, Silicon. 2013. “Improving the ADC Resolution by Oversampling and Averaging.” Silicon Laboratories.</div>
+  <div class="csl-entry"><a id="citeproc_bib_item_4"></a>Schmidt, R Munnig, Georg Schitter, and Adrian Rankers. 2020. <i>The Design of High Performance Mechatronics - Third Revised Edition</i>. Ios Press.</div>
+</div>