docs: Add papers

README.md

@@ -109,6 +109,8 @@ Have something to add or change? Open a [pull request](https://github.com/barbea
 - Wanninger and Anja Heßelbarth1. ["GNSS code and carrier phase observations of a Huawei P30 smartphone: quality assessment and centimeter-accurate positioning"](https://link.springer.com/content/pdf/10.1007/s10291-020-00978-z.pdf), GPS Solutions, 24:64, March 2020.
 - Jacek Paziewski, Marco Fortunato, Augusto Mazzoni, Robert Odolinski. ["An analysis of multi-GNSS observations tracked by recent Android smartphones and smartphone-only relative positioning results"](https://www.sciencedirect.com/science/article/pii/S0263224121001858), Measurement, Volume 175, 2021, https://doi.org/10.1016/j.measurement.2021.109162.
 - Ng, H-F, Zhang, G, Luo, Y, Hsu, L-T. ["Urban positioning: 3D mapping-aided GNSS using dual-frequency pseudorange measurements from smartphones."](https://www.ion.org/publications/abstract.cfm?articleID=102931) NAVIGATION. 2021; 68: 727– 749. https://doi.org/10.1002/navi.448
+- Yong et al. - ["Instantaneous, Dual-Frequency, Multi-GNSS Precise RTK Positioning Using Google Pixel 4 and Samsung Galaxy S20 Smartphones for Zero and Short Baselines"](https://www.mdpi.com/1424-8220/21/24/8318/htm), Sensors 2021, 21(24), 8318; https://doi.org/10.3390/s21248318.
+- Li et al. - ["Ambiguity resolution for smartphone GNSS precise positioning: effect factors and performance"](https://link.springer.com/article/10.1007/s00190-022-01652-7), Journal of Geodesy 96, 63 (2022). https://doi.org/10.1007/s00190-022-01652-7.
 
 ### Books