diff --git a/path_delay.bib b/path_delay.bib
index b2b668b..144754c 100644
--- a/path_delay.bib
+++ b/path_delay.bib
@@ -8,4 +8,81 @@ number={},
 pages={157 -159},
 keywords={Field programmable gate arrays;Frequency;Inverters;Propagation delay;Ring oscillators;Routing;Semiconductor device measurement;Testing;Timing;Wire;},
 doi={10.1109/SPI.2002.258304},
-ISSN={},}
\ No newline at end of file
+ISSN={},}
+
+@INPROCEEDINGS{pdm:vdl,
+author={Chan, AH. and Roberts, G.W.},
+booktitle={Test Conference, 2001. Proceedings. International},
+title={A synthesizable, fast and high-resolution timing measurement device using a component-invariant vernier delay line},
+year={2001},
+month={},
+pages={858-867},
+keywords={CMOS logic circuits;application specific integrated circuits;calibration;delay lines;electric variables measurement;field programmable gate arrays;integrated circuit testing;logic testing;timing;CMOS process;IC prototype;RTL description;calibration;component-invariant technique;differential nonlinearity timing errors;high-resolution timing measurement device;production test;register transfer level description;test time;vernier delay line technique;Circuit testing;Clocks;Counting circuits;Delay lines;Field programmable gate arrays;Performance evaluation;Phase measurement;Propagation delay;Ring oscillators;Timing jitter},
+doi={10.1109/TEST.2001.966708},
+ISSN={1089-3539},}
+
+@article{pdm:selfmeasurement,
+ author = {Wong, Justin S. J. and Sedcole, Pete and Cheung, Peter Y. K.},
+ title = {Self-Measurement of Combinatorial Circuit Delays in FPGAs},
+ journal = {ACM Trans. Reconfigurable Technol. Syst.},
+ issue_date = {June 2009},
+ volume = {2},
+ number = {2},
+ month = jun,
+ year = {2009},
+ issn = {1936-7406},
+ pages = {10:1--10:22},
+ articleno = {10},
+ numpages = {22},
+ url = {http://doi.acm.org/10.1145/1534916.1534920},
+ doi = {10.1145/1534916.1534920},
+ acmid = {1534920},
+ publisher = {ACM},
+ address = {New York, NY, USA},
+ keywords = {FPGA, Testing, configuration, delay measurement},
+} 
+
+@INPROCEEDINGS{pdm:ro0,
+author={Stanciu, A and Craciun, A},
+booktitle={Optimization of Electrical and Electronic Equipment (OPTIM), 2014 International Conference on},
+title={Generating an unique identifier for FPGA devices},
+year={2014},
+month={May},
+pages={802-808},
+keywords={BCH codes;error correction codes;error detection codes;field programmable gate arrays;logic design;oscillators;FPGA designs;FPGA devices;FPGA security technique;IP vendor;RO security;building automation;complex factories;control systems;cost reduction;device prototyping;digital circuits;electronic devices;hardware attacks;manufacturing flow;medical apparatus;motor controllers;ring oscillators;security issues;switches;system integrator;Encoding;Field programmable gate arrays;Generators;Hardware;Manufacturing;Ring oscillators},
+doi={10.1109/OPTIM.2014.6850952},}
+
+@INPROCEEDINGS{pdm:ro1,
+author={Jiliang Zhang and Qiang Wu and Yongqiang Lyu and Qiang Zhou and Yici Cai and Yaping Lin and Gang Qu},
+booktitle={Computer-Aided Design and Computer Graphics (CAD/Graphics), 2013 International Conference on},
+title={Design and Implementation of a Delay-Based PUF for FPGA IP Protection},
+year={2013},
+month={Nov},
+pages={107-114},
+keywords={copy protection;delays;digital rights management;field programmable gate arrays;industrial property;logic design;oscillators;Anderson PUF;FPGA IP protection;RO based PUF;arbiter-based PUF;challenge-response pairs;delay-based PUF;digital rights management;field programmable gate arrays;hard macros;intellectual property;key generation;physical unclonable function;resource overhead;ring oscillator;uncontrollable process variations;Delays;Fabrication;Field programmable gate arrays;Multiplexing;Random access memory;Shift registers;Table lookup;EDA;FPGAs;IP cores;fabrication variation;fingerprint;hardware security;intellectual property (IP) protection;physical unclonable functions (PUFs);watermarking},
+doi={10.1109/CADGraphics.2013.22},}
+
+
+@INPROCEEDINGS{pdm:routing,
+author={Zhua, K. and Yao-Wen Chang and Wong, D. F.},
+booktitle={Computer Design: VLSI in Computers and Processors, 1998. ICCD '98. Proceedings. International Conference on},
+title={Timing-driven routing for symmetrical-array-based FPGAs},
+year={1998},
+month={Oct},
+pages={628-633},
+keywords={circuit layout CAD;field programmable gate arrays;logic CAD;network routing;timing;FPGA;FPGAs;benchmark circuits;complexity;delay;routing resources;symmetrical-array-based;timing-driven global router;timing-driven routing trees;wirelength;Approximation algorithms;Circuit optimization;Delay;Field programmable gate arrays;Information science;Integrated circuit interconnections;Logic arrays;Routing;Switches;Timing},
+doi={10.1109/ICCD.1998.727132},
+ISSN={1063-6404},}
+
+@ARTICLE{pdm:routing1,
+author={Alexander, M.J. and Robins, G.},
+journal={Computer-Aided Design of Integrated Circuits and Systems, IEEE Transactions on},
+title={New performance-driven FPGA routing algorithms},
+year={1996},
+month={Dec},
+volume={15},
+number={12},
+pages={1505-1517},
+keywords={VLSI;circuit layout CAD;delays;field programmable gate arrays;integrated circuit design;logic CAD;logic partitioning;network routing;trees (mathematics);FPGA;Steiner algorithms;Steiner tree constructions;Xilinx parts;arborescence algorithms;channel width;optimal source-sink pathlengths;performance bounds;routing algorithms;routing solutions;wirelength;Algorithm design and analysis;Circuit simulation;Computer science;Construction industry;Field programmable gate arrays;Flexible printed circuits;Propagation delay;Routing;Steiner trees;Very large scale integration},
+doi={10.1109/43.552083},
+ISSN={0278-0070},}
\ No newline at end of file