* [Etch rates for micromachining processing, part 2](http://microlab.berkeley.edu/labmanual/chap1/JMEMSEtchRates2(2003).pdf)
* [Reproducible Electrochemical Etching of Tungsten Probe Tips](https://apmc.zyvex.com/literature/apmc-literature-surveys/stm-tip-fabrication/stm-tip-review/Reproducible%20Electrochemical%20Etching%20of%20Tungsten%20Probe%20Tips.pdf)
* [Tantalum oxide thin films as protective coatings for sensors](http://orbit.dtu.dk/getResource?recordId=266688&objectId=1&versionId=1)