Frequency Selection Database
Resource for USA frequency coordination and spectrum research.
http://www.spectrumwatch.com

Luff Research Inc.
Manufacture high performance RF frequency synthesizers and phase-locked frequency sources.
http://www.luffresearch.com/

ZZAP Elektronik d.o.o.
frequency converter, power supply, radio frequency reader, frekvencijski pretvaraci, izvori za napajanje, ups, radio frekvencijski citac, web design, web dizajn, electronic components, elektronicke komponente, konzalting, consulting, internet
http://www.zzap-elektronik.com

Liteline Electronics
Lightline Electronics, products for the motion picture industry. Maker of the CineSpeedMeter2 and other precision frequency measurement products.
http://www.lightlineelectronics.com

Liteline Electronics
Lightline Electronics, products for the motion picture industry. Maker of the CineSpeedMeter2 and other precision frequency measurement products.
http://www.lightlineelectronics.com

Elmika Microwave Technologies
Sweep oscilators, scalar and vector analizers, frequency converters, attenuators, frequency meters and waveguide components.
http://www.elmika.com/

References on Zipf's Law
An academic bibliography on this relation between a word's frequency in a text and its place in a ranking of words by frequency. Includes some online texts.
http://www.nslij-genetics.org/wli/zipf/index.html

Alexej Jerschow's Interactive NMR Frequency Map
Very useful resource. You enter the proton Frequency, the range you want to see, and the spin. The table prints out a very handy chart of the receptivety of the different nuclei.
http://www.nyu.edu/cgi-bin/cgiwrap/aj39/NMRmap.cgi

Frequency Electronics, Inc.
Provides frequency/time standards and synchronization products including quartz and atomic clocks, RF/microwave subsystems, DC/DC power converters, VSAT transceivers, and hybrids.
http://www.freqelec.com/

My Frequency Inc.
Manufactures frequency control devices including quartz crystals, crystal oscillators, VCXOs and TCXOs. Includes electrical and mechanical specifications and part numbering guide.
http://www.myfrequencyxtal.com/